&createFunction;
&createIndex;
&createLanguage;
+&createOperator;
+&createRule;
+&createSequence;
+&createTable;
&dropFunction;
&select;
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
--->
\ No newline at end of file
+-->
--- /dev/null
+<REFENTRY ID="SQL-CREATEOPERATOR-1">
+ <REFMETA>
+ <REFENTRYTITLE>
+ CREATE OPERATOR
+ </REFENTRYTITLE>
+ <REFMISCINFO>SQL - Language Statements</REFMISCINFO>
+ </REFMETA>
+ <REFNAMEDIV>
+ <REFNAME>
+ CREATE OPERATOR
+ </REFNAME>
+ <REFPURPOSE>
+ Defines a new user operator.
+ </REFPURPOSE>
+
+ <REFSYNOPSISDIV>
+ <REFSYNOPSISDIVINFO>
+ <DATE>1998-04-15</DATE>
+ </REFSYNOPSISDIVINFO>
+ <SYNOPSIS>
+ CREATE OPERATOR <replaceable>name</replaceable>
+ ([ LEFTARG = <replaceable class="parameter">type1</replaceable> ]
+ [, RIGHTARG = <replaceable class="parameter">type2</replaceable> ]
+ , PROCEDURE = <replaceable class="parameter">func_name</replaceable>
+ [, COMMUTATOR = <replaceable class="parameter">com_op</replaceable> ]
+ [, NEGATOR = <replaceable class="parameter">neg_op</replaceable> ]
+ [, RESTRICT = <replaceable class="parameter">res_proc</replaceable> ]
+ [, HASHES ]
+ [, JOIN = <replaceable class="parameter">join_proc</replaceable> ]
+ [, SORT = <replaceable class="parameter">sort_op</replaceable> [, ...] ]
+ )
+ </SYNOPSIS>
+
+ <REFSECT2 ID="R2-SQL-CREATEOPERATOR-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Inputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">name</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of an existing aggregate function.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">type1</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">type2</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">func_name</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">com_op</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">neg_op</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">res_proc</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">join_proc</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <replaceable class="parameter">sort_op</replaceable>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CREATEOPERATOR-2">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>CREATE</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Message returned if the operator is successfully created.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+ </REFSYNOPSISDIV>
+
+ <REFSECT1 ID="R1-SQL-CREATEOPERATOR-1">
+ <REFSECT1INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT1INFO>
+ <TITLE>
+ Description
+ </TITLE>
+ <PARA>
+ This command defines a new user operator, operator_name.
+ The user who defines an operator becomes its owner.
+ </para>
+ <para>
+ The operator_name is a sequence of up to sixteen punctua
+ tion characters. The following characters are valid for
+ single-character operator names:<literallayout>
+
+ ~ ! @ # % ^ & ` ? </literallayout>
+ </para>
+ <para>
+ If the operator name is more than one character long, it
+ may consist of any combination of the above characters or
+ the following additional characters:<literallayout>
+
+ | $ : + - * / < > =</literallayout>
+ </para>
+ <para>
+ The operator "!=" is mapped to "<>" on input, and they are
+ therefore equivalent.
+ </para>
+ <para>
+ At least one of leftarg and rightarg must be defined. For
+ binary operators, both should be defined. For right unary
+ operators, only arg1 should be defined, while for left
+ unary operators only arg2 should be defined.
+ </para>
+ <para>
+ The name of the operator, operator_name, can be composed
+ of symbols only. Also, the func_name procedure must have
+ been previously defined using create function(l) and must
+ have one or two arguments.
+ </para>
+ <para>
+ The commutator operator is present so that Postgres can
+ reverse the order of the operands if it wishes. For exam
+ ple, the operator area-less-than, >>>, would have a commu
+ tator operator, area-greater-than, <<<. Suppose that an
+ operator, area-equal, ===, exists, as well as an area not
+ equal, !==. Hence, the query optimizer could freely con
+ vert:
+ <programlisting>
+ "0,0,1,1"::box >>> MYBOXES.description
+ </programlisting>
+ to
+ <programlisting>
+ MYBOXES.description <<< "0,0,1,1"::box</programlisting>
+ </para>
+ <para>
+ This allows the execution code to always use the latter
+ representation and simplifies the query optimizer some
+ what.
+ </para>
+ <para>
+ The negator operator allows the query optimizer to convert
+ <programlisting>
+ NOT MYBOXES.description === "0,0,1,1"::box
+ </programlisting>
+ to
+ <programlisting>
+ MYBOXES.description !== "0,0,1,1"::box
+ </programlisting>
+ </para>
+ <para>
+ If a commutator operator name is supplied, Postgres
+ searches for it in the catalog. If it is found and it
+ does not yet have a commutator itself, then the commutator's
+ entry is updated to have the current (new) operator
+ as its commutator. This applies to the negator, as well.
+ </para>
+ <para>
+ This is to allow the definition of two operators that are
+ the commutators or the negators of each other. The first
+ operator should be defined without a commutator or negator
+ (as appropriate). When the second operator is defined,
+ name the first as the commutator or negator. The first
+ will be updated as a side effect.
+ </para>
+ <para>
+ The next two specifications are present to support the
+ query optimizer in performing joins. Postgres can always
+ evaluate a join (i.e., processing a clause with two tuple
+ variables separated by an operator that returns a boolean)
+ by iterative substitution [WONG76]. In addition, Postgres
+ is planning on implementing a hash-join algorithm along
+ the lines of [SHAP86]; however, it must know whether this
+ strategy is applicable. For example, a hash-join
+ algorithm is usable for a clause of the form:
+ <programlisting>
+ MYBOXES.description === MYBOXES2.description
+ </programlisting>
+ but not for a clause of the form:
+ <programlisting>
+ MYBOXES.description <<< MYBOXES2.description.
+ </programlisting>
+ The hashes flag gives the needed information to the query
+ optimizer concerning whether a hash join strategy is
+ usable for the operator in question.</para>
+ <para>
+ Similarly, the two sort operators indicate to the query
+ optimizer whether merge-sort is a usable join strategy and
+ what operators should be used to sort the two operand
+ classes. For the === clause above, the optimizer must
+ sort both relations using the operator, <<<. On the other
+ hand, merge-sort is not usable with the clause:
+ <programlisting>
+ MYBOXES.description <<< MYBOXES2.description
+ </programlisting>
+ </para>
+ <para>
+ If other join strategies are found to be practical, Post
+ gres will change the optimizer and run-time system to use
+ them and will require additional specification when an
+ operator is defined. Fortunately, the research community
+ invents new join strategies infrequently, and the added
+ generality of user-defined join strategies was not felt to
+ be worth the complexity involved.
+ </para>
+ <para>
+ The last two pieces of the specification are present so
+ the query optimizer can estimate result sizes. If a
+ clause of the form:
+ <programlisting>
+ MYBOXES.description <<< "0,0,1,1"::box
+ </programlisting>
+ is present in the qualification, then Postgres may have to
+ estimate the fraction of the instances in MYBOXES that
+ satisfy the clause. The function res_proc must be a reg
+ istered function (meaning it is already defined using
+ define function(l)) which accepts one argument of the correct
+ data type and returns a floating point number. The
+ query optimizer simply calls this function, passing the
+ parameter "0,0,1,1" and multiplies the result by the relation
+ size to get the desired expected number of instances.
+ </para>
+ <para>
+ Similarly, when the operands of the operator both contain
+ instance variables, the query optimizer must estimate the
+ size of the resulting join. The function join_proc will
+ return another floating point number which will be multiplied
+ by the cardinalities of the two classes involved to
+ compute the desired expected result size.
+ </para>
+ <para>
+ The difference between the function
+ <programlisting>
+ my_procedure_1 (MYBOXES.description, "0,0,1,1"::box)
+ </programlisting>
+ and the operator
+ <programlisting>
+ MYBOXES.description === "0,0,1,1"::box
+ </programlisting>
+ is that Postgres attempts to optimize operators and can
+ decide to use an index to restrict the search space when
+ operators are involved. However, there is no attempt to
+ optimize functions, and they are performed by brute force.
+ Moreover, functions can have any number of arguments while
+ operators are restricted to one or two.
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-CREATEOPERATOR-3">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Notes
+ </TITLE>
+ <PARA>
+ Refer to <citetitle>PostgreSQL User's Guide</citetitle> chapter 5
+ <comment>
+ This reference must be corrected.
+ </comment>
+ for further information.
+ Refer to DROP OPERATOR statement to drop operators.
+
+ </REFSECT2>
+
+ <REFSECT1 ID="R1-SQL-CREATEOPERATOR-2">
+ <TITLE>
+ Usage
+ </TITLE>
+ <PARA>The following command defines a new operator,
+ area-equality, for the BOX data type.
+ </PARA>
+ <ProgramListing>
+ CREATE OPERATOR === (
+ LEFTARG = box,
+ RIGHTARG = box,
+ PROCEDURE = area_equal_procedure,
+ COMMUTATOR = ===,
+ NEGATOR = !==,
+ RESTRICT = area_restriction_procedure,
+ HASHES,
+ JOIN = area-join-procedure,
+ SORT = <<<, <<<)
+ </ProgramListing>
+
+
+ </REFSECT1>
+
+ <REFSECT1 ID="R1-SQL-CREATEOPERATOR-3">
+ <TITLE>
+ Compatibility
+ </TITLE>
+ <PARA>
+ CREATE OPERATOR is a PostgreSQL extension of SQL.
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-CREATEOPERATOR-4">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ SQL92
+ </TITLE>
+ <PARA>
+ There is no CREATE OPERATOR statement on SQL92.
+ </PARA>
+ </refsect2>
+ </refsect1>
+</REFENTRY>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+sgml-parent-document:nil
+sgml-default-dtd-file:"../reference.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:"/usr/lib/sgml/catalog"
+sgml-local-ecat-files:nil
+End:
+-->
--- /dev/null
+<REFENTRY ID="SQL-CREATERULE-1">
+ <REFMETA>
+ <REFENTRYTITLE>
+ CREATE RULE
+ </REFENTRYTITLE>
+ <REFMISCINFO>SQL - Language Statements</REFMISCINFO>
+ </REFMETA>
+ <REFNAMEDIV>
+ <REFNAME>
+ CREATE RULE
+ </REFNAME>
+ <REFPURPOSE>
+ Defines a new rule.
+ </REFPURPOSE>
+ <REFSYNOPSISDIV>
+ <REFSYNOPSISDIVINFO>
+ <DATE>1998-04-15</DATE>
+ </REFSYNOPSISDIVINFO>
+ <SYNOPSIS>
+ CREATE RULE <replaceable class="parameter">name</replaceable>
+ AS ON <replaceable class="parameter">event</replaceable>
+ TO <replaceable class="parameter">object</replaceable> [WHERE <replaceable class="parameter">condition</replaceable>]
+ DO [INSTEAD]
+ [<replaceable class="parameter">action</replaceable> | NOTHING ]
+ </SYNOPSIS>
+
+ <REFSECT2 ID="R2-SQL-CREATERULE-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Inputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">name</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of a rule to create.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">event</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Event is one of <literal>select</literal>, <literal>update</literal>, <literal>delete</literal> or <literal>insert</literal>.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">object</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Object is either <replaceable class="parameter">table</replaceable> or <replaceable class="parameter">table</replaceable>.<replaceable class="parameter">column</replaceable>.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">condition</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Any SQL <literal>where</literal> clause. <literal>new</literal> or
+ <literal>current</literal> can appear instead of an instance
+ variable whenever an instance variable is permissible in SQL.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">action</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Any SQL-statement. <literal>new</literal> or
+ <literal>current</literal> can appear instead of an instance
+ variable whenever an instance variable is permissible in SQL.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CREATERULE-2">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>CREATE</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Message returned if the rule is successfully created.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+
+ </REFSECT2>
+ </REFSYNOPSISDIV>
+
+ <REFSECT1 ID="R1-SQL-CREATERULE-1">
+ <REFSECT1INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT1INFO>
+ <TITLE>
+ Description
+ </TITLE>
+ <PARA>
+ The semantics of a rule is that at the time an individual instance is
+ accessed, updated, inserted or deleted, there is a current instance (for
+ retrieves, updates and deletes) and a new instance (for updates and
+ appends). If the <replaceable class="parameter">event</replaceable>
+ specified in the <literal>on</literal> clause and the
+ <replaceable class="parameter">condition</replaceable> specified in the
+ <literal>where</literal> clause are true for the current instance, the
+ <replaceable class="parameter">action</replaceable> part of the rule is
+ executed. First, however, values from fields in the current instance
+ and/or the new instance are substituted for
+ <literal> current.</literal><replaceable class="parameter">attribute-name</replaceable>
+ and <literal>new.</literal><replaceable class="parameter">attribute-name</replaceable>.
+ </para>
+ <para>
+ The <replaceable class="parameter">action</replaceable> part of the rule
+ executes with the same command and transaction identifier as the user
+ command that caused activation.
+ </para>
+
+ <REFSECT2 ID="R2-SQL-CREATERULE-3">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Notes
+ </TITLE>
+ <para>
+ A note of caution about SQL rules is in order. If the same class name
+ or instance variable appears in the
+ <replaceable class="parameter">event</replaceable>, the
+ <replaceable class="parameter">condition</replaceable> and the
+ <replaceable class="parameter">action</replaceable> parts of a rule,
+ they are all considered different tuple variables. More accurately,
+ <literal>new</literal> and <literal>current</literal> are the only tuple
+ variables that are shared between these clauses. For example, the following
+ two rules have the same semantics:
+ <programlisting>
+ on update to EMP.salary where EMP.name = "Joe"
+ do update EMP ( ... ) where ...
+
+ on update to EMP-1.salary where EMP-2.name = "Joe"
+ do update EMP-3 ( ... ) where ...
+ </programlisting>
+ Each rule can have the optional tag <literal>instead</literal>. Without
+ this tag, <replaceable class="parameter">action</replaceable> will be
+ performed in addition to the user command when the
+ <replaceable class="parameter">event</replaceable> in the
+ <replaceable class="parameter">condition</replaceable> part of the rule
+ occurs. Alternately, the
+ <replaceable class="parameter">action</replaceable> part will be done
+ instead of the user command. In this later case, the
+ <replaceable class="parameter">action</replaceable> can be the keyword
+ <literal>nothing</literal>.
+ </para>
+ <para>
+ When choosing between the rewrite and instance rule systems for a
+ particular rule application, remember that in the rewrite system,
+ <literal>current</literal> refers to a relation and some qualifiers
+ whereas in the instance system it refers to an instance (tuple).
+ </para>
+ <para>
+ It is very important to note that the rewrite rule system
+ will neither detect nor process circular rules. For example, though each
+ of the following two rule definitions are accepted by Postgres, the
+ retrieve command will cause Postgres to crash:
+ <example>
+ <title>Example of a circular rewrite rule combination.</title>
+ <programlisting>
+ create rule bad_rule_combination_1 is
+ on select to EMP
+ do instead select to TOYEMP
+
+ create rule bad_rule_combination_2 is
+ on select to TOYEMP
+ do instead select to EMP
+ </programlisting>
+ <para>
+ This attempt to retrieve from EMP will cause Postgres to crash.
+ <programlisting>
+ select * from EMP
+ </programlisting></para>
+ </example>
+ </para>
+ <para>
+ You must have rule definition access to a class in order
+ to define a rule on it (see change acl(l)).
+ <comment>
+ There is no manpage change or change_acl. What is intended?
+ </comment>
+ </PARA>
+ </REFSECT2>
+ </refsect1>
+
+ <REFSECT1 ID="R1-SQL-CREATERULE-2">
+ <TITLE>
+ Usage
+ </TITLE>
+ <PARA>
+ Make Sam get the same salary adjustment as Joe
+
+ <programlisting>
+ create rule example_1 is
+ on update EMP.salary where current.name = "Joe"
+ do update EMP (salary = new.salary)
+ where EMP.name = "Sam"
+ </programlisting>
+
+ At the time Joe receives a salary adjustment, the event
+ will become true and Joe's current instance and proposed
+ new instance are available to the execution routines.
+ Hence, his new salary is substituted into the action part
+ of the rule which is subsequently executed. This propagates
+ Joe's salary on to Sam.
+ </para>
+ <para>
+ Make Bill get Joe's salary when it is accessed
+ <programlisting>
+ create rule example_2 is
+
+ on select to EMP.salary
+ where current.name = "Bill"
+ do instead
+ select (EMP.salary) from EMP where EMP.name = "Joe"
+ </programlisting>
+ </para>
+ <para>
+ Deny Joe access to the salary of employees in the shoe
+ department. (<function>pg_username()</function> returns the name of
+ the current user)
+ <programlisting>
+ create rule example_3 is
+ on select to EMP.salary
+ where current.dept = "shoe" and pg_username() = "Joe"
+ do instead nothing
+ </programlisting>
+ </para>
+ <para>
+ Create a view of the employees working in the toy department.
+ <programlisting>
+ create TOYEMP(name = char16, salary = int4)
+
+ create rule example_4 is
+ on select to TOYEMP
+ do instead select (EMP.name, EMP.salary) from EMP
+ where EMP.dept = "toy"
+ </programlisting>
+ </para>
+ <para>
+ All new employees must make 5,000 or less
+ <programlisting>
+ create rule example_5 is
+ on insert to EMP where new.salary > 5000
+ do update newset salary = 5000
+ </programlisting>
+ </PARA>
+ </REFSECT1>
+
+ <REFSECT1 ID="R1-SQL-CREATERULE-3">
+ <TITLE>
+ Bugs
+ </TITLE>
+ <PARA>
+ <literal>instead</literal> rules do not work properly.
+ </para>
+ <para>
+ The object in a SQL rule cannot be an array reference and
+ cannot have parameters.
+ </para>
+ <para>
+ Aside from the "oid" field, system attributes cannot be
+ referenced anywhere in a rule. Among other things, this
+ means that functions of instances (e.g., "<literal>foo(emp)</literal>" where
+ "<literal>emp</literal>" is a class) cannot be called anywhere in a rule.
+ </para>
+ <para>
+ The rule system stores the rule text and query plans as
+ text attributes. This implies that creation of rules may
+ fail if the rule plus its various internal representations
+ exceed some value that is on the order of one page (8KB).
+ </PARA>
+
+ <REFSECT1 ID="R1-SQL-CREATERULE-4">
+ <TITLE>
+ Compatibility
+ </TITLE>
+ <PARA>
+ CREATE RULE statement is a PostgreSQL language extension.
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-CREATERULE-4">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ SQL92
+ </TITLE>
+ <para>
+ There is no CREATE RULE statement in SQL92.
+ </para>
+ </refsect2>
+ </refsect1>
+</REFENTRY>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+sgml-parent-document:nil
+sgml-default-dtd-file:"../reference.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:"/usr/lib/sgml/catalog"
+sgml-local-ecat-files:nil
+End:
+-->
--- /dev/null
+<REFENTRY ID="SQL-CREATESEQUENCE-1">
+ <REFMETA>
+ <REFENTRYTITLE>
+ CREATE SEQUENCE
+ </REFENTRYTITLE>
+ <REFMISCINFO>SQL - Language Statements</REFMISCINFO>
+ </REFMETA>
+ <REFNAMEDIV>
+ <REFNAME>
+ CREATE SEQUENCE
+ </REFNAME>
+ <REFPURPOSE>
+ creates a new sequence number generator.
+ </REFPURPOSE>
+
+ <REFSYNOPSISDIV>
+ <REFSYNOPSISDIVINFO>
+ <DATE>1998-04-15</DATE>
+ </REFSYNOPSISDIVINFO>
+ <SYNOPSIS>
+ CREATE SEQUENCE <replaceable class="parameter">seqname</replaceable>
+ [INCREMENT <replaceable class="parameter">increment</replaceable>]
+ [MINVALUE <replaceable class="parameter">minvalue</replaceable>]
+ [MAXVALUE <replaceable class="parameter">maxvalue</replaceable>]
+ [START <replaceable class="parameter">start</replaceable>]
+ [CACHE <replaceable class="parameter">cache</replaceable>]
+ [CYCLE]
+ </SYNOPSIS>
+
+ <REFSECT2 ID="R2-SQL-CREATESEQUENCE-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Inputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">seqname</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of a sequence to be created.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">increment</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The <option>INCREMENT <replaceable class="parameter">increment</replaceable></option> clause is optional. A positive value will make an
+ ascending sequence, a negative one a descending sequence. The default value
+ is 1.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">minvalue</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional clause <option>MINVALUE
+ <replaceable class="parameter">minvalue</replaceable></option>
+ determines the minimum value
+ a sequence can be. The defaults are 1 and -2147483647 for
+ ascending and descending sequences, respectively.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">maxvalue</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Use the optional clause <option>MAXVALUE
+ <replaceable class="parameter">maxvalue</replaceable></option> to
+ determine the maximum
+ value for the sequence. The defaults are 2147483647 and -1 for
+ ascending and descending sequences, respectively.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">start</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional <option>START
+ <replaceable class="parameter">start</replaceable>
+ clause</option> enables the sequence to begin anywhere.
+ The default starting value is
+ <replaceable class="parameter">minvalue</replaceable>
+ for ascending sequences and
+ <replaceable class="parameter">maxvalue</replaceable>
+ for descending ones.
+ <comment>
+ What happens if the user specifies start outside the range?
+ </comment>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">cache</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The <option>CACHE <replaceable class="parameter">cache</replaceable></option> option
+ enables sequence numbers to be preallocated
+ and stored in memory for faster access. The minimum
+ value is 1 (no cache) and this is also the default.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>CYCLE</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional CYCLE keyword may be used to enable the sequence
+ to continue when the
+ <replaceable class="parameter">maxvalue</replaceable> or
+ <replaceable class="parameter">minvalue</replaceable> has been
+ reached by
+ an ascending or descending sequence respectively. If the limit is
+ reached, the next number generated will be whatever the
+ <replaceable class="parameter">minvalue</replaceable> or
+ <replaceable class="parameter">maxvalue</replaceable> is,
+ as appropriate.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CREATESEQUENCE-2">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>CREATE</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Message returned if the command is successful.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>ERROR: amcreate: '<replaceable class="parameter"> seqname</replaceable>' relation already exists</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ If the sequence specified already exists.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+ </REFSYNOPSISDIV>
+
+ <REFSECT1 ID="R1-SQL-CREATESEQUENCE-1">
+ <REFSECT1INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT1INFO>
+ <TITLE>
+ Description
+ </TITLE>
+ <PARA>
+ CREATE SEQUENCE will enter a new sequence number generator
+ into the current data base. This involves creating and initialising a
+ new single block
+ table with the name <replaceable class="parameter">seqname</replaceable>.
+ The generator will be "owned" by the user issuing the command.
+ </PARA>
+ <para>
+ After the sequence is created, you may use the function
+ <function>nextval()</function> with the
+ sequence name as the argument to get a new number from the sequence.
+ The function <function>currval('<replaceable class="parameter">sequence_name</replaceable>')</function> may be used
+ to determine the number returned by the last call to
+ <function>nextval()</function> for the
+ specified sequence in the current session.
+ </para>
+
+ <para>
+ Use a query like
+ <programlisting>
+ SELECT * FROM sequence_name;
+ </programlisting>
+ to get the parameters of a sequence.
+ </para>
+ <para>
+ Low-level locking is used to enable multiple simultaneous
+ calls to a generator.
+ </para>
+
+ <REFSECT2 ID="R2-SQL-CREATESEQUENCE-3">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Notes
+ </TITLE>
+ <PARA>
+ Refer to the DROP SEQUENCE statement to remove a sequence.
+ </PARA>
+ <para>
+ Each backend uses its own cache to store allocated numbers.
+ Numbers that are cached but not used in the current session will be
+ lost.
+ </para>
+ </REFSECT2>
+ </refsect1>
+
+ <REFSECT1 ID="R1-SQL-CREATESEQUENCE-2">
+ <TITLE>
+ Usage
+ </TITLE>
+ <PARA>
+ Create an ascending sequence called serial, starting at 101:
+ </PARA>
+ <ProgramListing>
+ CREATE SEQUENCE serial START 101;
+ </ProgramListing>
+ <para>
+ Select the next number from this sequence
+ <programlisting>
+ SELECT NEXTVAL ('serial');
+
+ nextval
+ -------
+ 114
+ </programlisting>
+ </para>
+ <para>
+ Use this sequence in an INSERT:
+ <programlisting>
+ INSERT INTO distributors VALUES (NEXTVAL ('serial'),'nothing');
+ </programlisting>
+ </para>
+ </REFSECT1>
+
+ <REFSECT1 ID="R1-SQL-CREATESEQUENCE-3">
+ <TITLE>
+ Compatibility
+ </TITLE>
+ <PARA>
+ CREATE SEQUENCE statement is a PostgreSQL language extension.
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-CREATESEQUENCE-4">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ SQL92
+ </TITLE>
+ <PARA>
+ There is no CREATE SEQUENCE statement on SQL92.
+ </PARA>
+ </refsect2>
+ </refsect1>
+</REFENTRY>
+
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+sgml-parent-document:nil
+sgml-default-dtd-file:"../reference.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:"/usr/lib/sgml/catalog"
+sgml-local-ecat-files:nil
+End:
+-->
--- /dev/null
+<REFENTRY ID="SQL-CREATETABLE-1">
+ <REFMETA>
+ <REFENTRYTITLE>
+ CREATE TABLE
+ </REFENTRYTITLE>
+ <REFMISCINFO>SQL - Language Statements</REFMISCINFO>
+ </REFMETA>
+ <REFNAMEDIV>
+ <REFNAME>
+ CREATE TABLE
+ </REFNAME>
+ <REFPURPOSE>
+ Creates a new table.
+ </REFPURPOSE>
+
+ <REFSYNOPSISDIV>
+ <REFSYNOPSISDIVINFO>
+ <DATE>1998-04-15</DATE>
+ </REFSYNOPSISDIVINFO>
+ <SYNOPSIS>
+ CREATE TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE> (
+ <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">type</REPLACEABLE> [DEFAULT <REPLACEABLE CLASS="PARAMETER">value</REPLACEABLE>] [CONSTRAINT <REPLACEABLE CLASS="PARAMETER">column_constraint</REPLACEABLE>] [, ...]
+ [, <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> ...]
+ [, CONSTRAINT <REPLACEABLE CLASS="PARAMETER">table_constraint</REPLACEABLE>]
+ ) [INHERITS ( <REPLACEABLE CLASS="PARAMETER">inherited_table</REPLACEABLE> [, ...] )]
+ </SYNOPSIS>
+
+ <REFSECT2 ID="R2-SQL-CREATETABLE-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Inputs
+ </TITLE>
+ <PARA>
+ </PARA>
+
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of a new table to be created.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of a column.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">type</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The type of the column.
+ (Refer to the <ProductName>Postgres</ProductName> User's Guide for
+ further information about data types).
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">value</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ A default value for a column.
+ See the DEFAULT clause for more information.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">inherited_table</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional INHERITS clause specifies a collection of table
+ names from which this table automatically inherits all fields.
+ If any inherited field name appears more than once, PostgreSQL
+ reports an error. PostgreSQL automatically allows the created
+ table to inherit functions on tables above it in the inheritance
+ hierarchy. Inheritance of functions is done according
+ to the conventions of the Common Lisp Object System (CLOS).
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <REPLACEABLE CLASS="PARAMETER">column_constraint</REPLACEABLE>
+ <REPLACEABLE CLASS="PARAMETER">table_constraint</REPLACEABLE>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional CONSTRAINT clause specifies a list of integrity
+ constraints which new or updated entries must satisfy for
+ an insert or update operation to succeed. Each constraint
+ must evaluate to a boolean expression. Multiple columns
+ may be referenced within a single constraint.
+ See CONSTRAINT clause for more information.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+
+
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CREATETABLE-2">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>status</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>CREATE</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Message returned if table is successfully created.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>ERROR</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Message returned if table creation failed.
+ This is usually accompanied by some descriptive text, such as:
+ <ProgramListing>
+ amcreate: "<replaceable class="parameter">table</replaceable>" relation already exists
+ </ProgramListing>
+ which occurs at runtime, if the table specified already exists
+ in the database.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+ </REFSYNOPSISDIV>
+
+ <REFSECT1 ID="R1-SQL-CREATETABLE-1">
+ <REFSECT1INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT1INFO>
+ <TITLE>
+ Description
+ </TITLE>
+ <PARA>
+ CREATE TABLE will enter a new table into the current data
+ base. The table will be "owned" by the user issuing the
+ command.
+
+ <PARA>
+ The new table is created as a heap with no initial data.
+ A table can have no more than 1600 columns (realistically,
+ this is limited by the fact that tuple sizes must
+ be less than 8192 bytes), but this limit may be configured
+ lower at some sites. A table cannot have the same name as
+ a system catalog table.
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-DEFAULTCLAUSE-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ DEFAULT clause
+ </TITLE>
+ <PARA>
+ <SYNOPSIS>
+ DEFAULT <REPLACEABLE CLASS="PARAMETER">value</REPLACEABLE>
+ </SYNOPSIS>
+ <PARA>
+ The DEFAULT clause assigns a default data value to a column.
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">value</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The possible values for expression are:
+ <itemizedlist>
+ <listitem>
+ <simpara>
+ a literal value
+ </simpara>
+ </listitem>
+ <listitem>
+ <simpara>
+ a user function
+ </simpara>
+ </listitem>
+ <listitem>
+ <simpara>
+ a niladic function
+ </simpara>
+ </listitem>
+ </itemizedlist>
+ </para>
+ </listitem>
+ </VARLISTENTRY>
+
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>ERROR: DEFAULT: type mismatched</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ if data type of default value doesn't match the
+ column definition's data type.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ <PARA>
+ The DEFAULT clause assigns a default data value to a column
+ (via a column definition in the CREATE TABLE statement).
+ The data type of a default value must match the column definition's
+ data type.
+ </PARA>
+ <PARA>
+ An INSERT operation that includes a column without a specified
+ default value will assign the NULL value to the column
+ if no explicit data value is provided for it.
+ Default <replaceable class="parameter">literal</replaceable> means
+ that the default is the specified constant value.
+ Default <replaceable class="parameter">niladic-function</replaceable>
+ or <replaceable class="parameter">user-function</replaceable> means
+ that the default
+ is the value of the specified function at the time of the INSERT.
+ </PARA>
+ <PARA>
+ There are two types of niladic functions:<variablelist>
+ <varlistentry>
+ <term>niladic USER</term>
+ <listitem>
+ <variablelist>
+ <varlistentry>
+ <term>CURRENT_USER / USER</term>
+ <listitem>
+ <simpara>See CURRENT_USER function</simpara>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>SESSION_USER</term>
+ <listitem>
+ <simpara>not yet supported</simpara>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>SYSTEM_USER</term>
+ <listitem>
+ <simpara>not yet supported</simpara>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>niladic datetime</term>
+ <listitem>
+ <variablelist>
+ <varlistentry>
+ <term> CURRENT_DATE</term>
+ <listitem>
+ <simpara>See CURRENT_DATE function</simpara>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>CURRENT_TIME</term>
+ <listitem>
+ <simpara>See CURRENT_TIME function</simpara>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>CURRENT_TIMESTAMP</term>
+ <listitem>
+ <simpara>See CURRENT_TIMESTAMP function</simpara>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-NOTNULL-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ NOT NULL constraint
+ </TITLE>
+ <SYNOPSIS>
+ [ CONSTRAINT <replaceable class="parameter">name</replaceable> ] NOT NULL
+ </SYNOPSIS>
+ <PARA>
+ The NOT NULL constraint specifies a rule that a column may
+ contain only non-null values.
+ </PARA>
+ <PARA>
+ The NOT NULL constraint is a column constraint.
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">name</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The optional name of a constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+
+ <REFSECT3 ID="R3-SQL-NOTNULL-1">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>ERROR: ExecAppend: Fail to add null value in not
+ null attribute "<replaceable class="parameter">column</replaceable>".</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ This error occurs at runtime if one tries to insert a null value
+ into a column which has a NOT NULL constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </REFSECT3>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-UNIQUECLAUSE-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ UNIQUE constraint
+ </TITLE>
+ <para>
+ Table Constraint definition
+ </para>
+ <synopsis>
+ [ CONSTRAINT <replaceable class="parameter">name</replaceable> ] UNIQUE ( <replaceable class="parameter">column</replaceable> [, ...] )
+ </SYNOPSIS>
+ <para>
+ Column Constraint definition
+ </para>
+ <synopsis>
+ [ CONSTRAINT <replaceable class="parameter">name</replaceable> ] UNIQUE
+ </SYNOPSIS>
+ <refsect3>
+ <title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <replaceable class="parameter">name</replaceable>
+ </term>
+ <listitem>
+ <para>
+ An arbitrary name given to a constraint.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>
+ <replaceable class="parameter">column</replaceable>
+ </term>
+ <listitem>
+ <para>
+ A name of a column in a table.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect3>
+ <refsect3>
+ <title>Outputs</title>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ ERROR: Cannot insert a duplicate key into a unique index.
+ </term>
+ <listitem>
+ <para>
+ This error occurs at runtime if one tries to insert a
+ duplicate value into a column.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect3>
+ <refsect3>
+ <title>Description</title>
+ <PARA>
+ The UNIQUE constraint specifies a rule that a group of one or
+ more distinct columns of a table may contain only unique values.
+ </para>
+ <para>
+ The column definitions of the specified columns do not have to
+ include a NOT NULL constraint to be included in a UNIQUE
+ constraint. Having more than one null value in a column without a
+ NOT NULL constraint, does not violate a UNIQUE constraint.
+ </PARA>
+ <PARA>
+ Each UNIQUE constraint must name a set of columns that is
+ different from the set of columns named by any other UNIQUE or
+ PRIMARY KEY constraint defined for the Table.
+ </PARA>
+ <Note>
+ <Para>
+ PostgreSQL automatically creates a unique index for each UNIQUE
+ constraint, to assure
+ data integrity. See CREATE INDEX for more information.
+ </Para>
+ </Note>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CONSTRAINT-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ CONSTRAINT clause
+ </TITLE>
+ <para>
+ Table constraint definition
+ </para>
+ <SYNOPSIS>
+ [ CONSTRAINT name ]
+ { PRIMARY KEY constraint |
+ UNIQUE constraint |
+ CHECK constraint }
+ </SYNOPSIS>
+ <PARA>
+ Column constraint definition
+ </PARA>
+ <SYNOPSIS>
+ [ CONSTRAINT name ]
+ { NOT NULL constraint |
+ PRIMARY KEY constraint |
+ UNIQUE constraint |
+ CHECK constraint }
+ </SYNOPSIS>
+ <PARA>
+ </PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>
+ <replaceable class="parameter">name</replaceable>
+ </ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ An arbitrary name given to an integrity constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>
+ <replaceable class="parameter">constraint</replaceable>
+ </ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The definition of the constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ <para>
+ A Constraint is a named rule: a SQL object which helps define
+ valid sets of values by putting limits on the results of INSERT,
+ UPDATE or DELETE operations performed on a Base table.
+ </para>
+ <para>
+ There are two ways to define integrity constraints:
+ Table constraint and Column constraint.
+ </para>
+ <para>
+ A Table Constraint is an integrity Constraint defined on one or
+ more Columns of a Base table. The four variations of "Table
+ Constraint" are:
+ <simplelist columns="1">
+ <member>PRIMARY KEY</member>
+ <member>FOREIGN KEY</member>
+ <member>UNIQUE</member>
+ <member>CHECK</member>
+ </simplelist>
+ </para>
+ <para>
+ A column constraint is an integrity constraint defined as part
+ of a column definition, and logically becomes a table
+ constraint as soon as it is created. The column
+ constraints available are:
+ <simplelist columns="1">
+ <member>PRIMARY KEY</member>
+ <member>REFERENCES</member>
+ <member>UNIQUE</member>
+ <member>CHECK</member>
+ <member>NOT NULL</member>
+ </simplelist></para>
+ <note>
+ <para>
+ PostgreSQL does not yet (at release 6.3.2) support the FOREIGN KEY or
+ REFERENCES integrity constraints, although the parser will accept them.
+ Foreign keys may be partially emulated by triggers (See CREATE TRIGGER
+ statement)
+ </para>
+ </note>
+ <note>
+ <para>
+ PostgreSQL does not yet support either DOMAINs or ASSERTIONs.
+ </para>
+ </note>
+
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-CHECK-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <title>The CHECK constraint</title>
+ <SYNOPSIS>
+ [ CONSTRAINT name ] CHECK ( condition [, ...] )
+ </SYNOPSIS>
+ <refsect3 id="R3-SQL-CHECK-1">
+ <title>Inputs</title>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><replaceable class="parameter">name</replaceable></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ An arbitrary name given to a constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>condition</ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ Any valid conditional expression.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </REFSECT3>
+
+ <REFSECT3 ID="R3-SQL-CHECK-2">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ Outputs
+ </TITLE>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue>
+ ERROR: ExecAppend: rejected due to CHECK constraint
+ "<replaceable class="parameter">table_column</replaceable>".
+ </ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ This error occurs at runtime if one tries to insert an illegal
+ value into a column subject to a CHECK constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </variablelist>
+ </REFSECT3>
+ <refsect3>
+ <title>Description</title>
+ <para>
+ The CHECK constraint specifies a rule that a group of one or
+ more columns of a table may contain only those values allowed by
+ the rule.
+ </para>
+ <PARA>
+ The CHECK constraint is either a table constraint or a column
+ constraint.
+ </PARA>
+ <PARA>
+ PostgreSQL automatically creates an unique index to assure
+ data integrity. (See CREATE INDEX statement)
+ </PARA>
+ <PARA>
+ The SQL92 CHECK column constraints can only be defined on, and
+ refer to, one column of the table. PostgreSQL does not have
+ this restriction.
+ </PARA>
+ </refsect3>
+ <refsect3>
+ <title>BUGS in CHECK constraint</title>
+ <PARA>
+ The following CHECK constraints gives a parse error like:
+ <programlisting>
+ ERROR: parser: parse error at or near "opname":
+ </programlisting>
+ <simplelist columns="1">
+ <member>CHECK ( <replaceable class="parameter">column</replaceable> BETWEEN 'A' AND 'Z' )</member>
+ <member>CHECK ( <replaceable class="parameter">column</replaceable> IN ('A','Z'))</member>
+ <member>CHECK ( <replaceable class="parameter">column</replaceable> NOT LIKE 'A%')</member>
+ </simplelist>
+ </para>
+ </refsect3>
+ </REFSECT2>
+
+ <REFSECT2 ID="R2-SQL-PRIMARYKEY-1">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ PRIMARY KEY clause
+ </TITLE>
+ <PARA>
+ Table constraint definition
+ </PARA>
+ <SYNOPSIS>
+ [ CONSTRAINT <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> ] PRIMARY KEY ( <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [, ...] )
+ </SYNOPSIS>
+ <PARA>
+ Column constraint definition
+ </PARA>
+ <SYNOPSIS>
+ [ CONSTRAINT <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> ] PRIMARY KEY
+ </SYNOPSIS>
+
+ <refsect3>
+ <title>Parameters</title>
+ <PARA>
+ <VARIABLELIST>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ An arbitrary name for the constraint.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ <VARLISTENTRY>
+ <TERM>
+ <ReturnValue><REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE></ReturnValue>
+ </TERM>
+ <LISTITEM>
+ <PARA>
+ The name of a column in the table.
+ </PARA>
+ </LISTITEM>
+ </VARLISTENTRY>
+ </VARIABLELIST>
+ </para>
+ </refsect3>
+ <refsect3>
+ <title>Outputs</title>
+ <variablelist>
+ <varlistentry>
+ <term>ERROR: Cannot insert a duplicate key into a unique index.</term>
+ <listitem>
+ <para>
+ This occurs at run-time if one tries to insert a duplicate value into
+ a column subject to a PRIMARY KEY constraint.
+ </PARA>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect3>
+ <refsect3>
+ <title>Description</title>
+ <PARA>
+ The PRIMARY KEY constraint specifies a rule that a group of one
+ or more distinct columns of a table may contain only unique,
+ (not duplicates), non-null values. The column definitions of
+ the specified columns do not have to include a NOT NULL
+ constraint to be included in a PRIMARY KEY constraint.
+ </PARA>
+ <PARA>
+ A table's set of valid values may be constrained by only one
+ PRIMARY KEY constraint at a time.
+ </PARA>
+ <PARA>
+ The PRIMARY KEY constraint must name a set of columns that is
+ different from the set of columns named by any UNIQUE constraint
+ defined for the same table.
+ </PARA>
+ </REFSECT3>
+
+ <REFSECT3 ID="R3-SQL-PRIMARYKEY-3">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ Notes
+ </TITLE>
+ <PARA>
+ PostgreSQL automatically creates an unique index to assure
+ data integrity. (See CREATE INDEX statement)
+ </PARA>
+ </refsect3>
+
+ </REFSECT2>
+ </refsect1>
+
+ <REFSECT1 ID="R1-SQL-CREATETABLE-2">
+ <TITLE>
+ Usage
+ </TITLE>
+ <PARA>
+ Create table films and table distributors
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE films (
+ code CHARACTER(5) CONSTRAINT firstkey PRIMARY KEY,
+ title CHARACTER VARYING(40) NOT NULL,
+ did DECIMAL(3) NOT NULL,
+ date_prod DATE,
+ kind CHAR(10),
+ len INTERVAL HOUR TO MINUTE
+ );
+ </ProgramListing>
+
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(03) PRIMARY KEY DEFAULT NEXTVAL('serial'),
+ name VARCHAR(40) NOT NULL CHECK (name <> '')
+ );
+ </ProgramListing>
+
+ <PARA>
+ Create a table with a 2-dimensional array
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE array (
+ vector INT[][]
+ );
+ </ProgramListing>
+
+ <PARA>
+ Define two NOT NULL column constraints on the table distributors
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(3) CONSTRAINT no_null NOT NULL,
+ name VARCHAR(40) NOT NULL
+ );
+ </ProgramListing>
+
+ <PARA>
+ Define a UNIQUE table constraint for the table films.
+ UNIQUE table constraints can be defined on one or more
+ columns of the table
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE films (
+ code CHAR(5),
+ title VARCHAR(40),
+ did DECIMAL(03),
+ date_prod DATE,
+ kind CHAR(10),
+ len INTERVAL HOUR TO MINUTE,
+ CONSTRAINT production UNIQUE(date_prod)
+ );
+ </ProgramListing>
+
+ <PARA>
+ Defines a UNIQUE column constraint for the table distributors.
+ UNIQUE column constraints can only be defined on one column
+ of the table (the following two examples are equivalents).
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(03),
+ name VARCHAR(40) UNIQUE,
+ UNIQUE(name)
+ );
+ </ProgramListing>
+
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(3),
+ name VARCHAR(40) UNIQUE
+ );
+ </ProgramListing>
+
+ <PARA>
+ Define a CHECK column constraint.
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(3) CHECK (did > 100),
+ name VARCHAR(40)
+ );
+ </ProgramListing>
+
+ <PARA>
+ Define a CHECK table constraint
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(3),
+ name VARCHAR(40)
+ CONSTRAINT con1 CHECK (did > 100 AND name > '')
+ );
+ </ProgramListing>
+
+ <PARA>
+ Define a PRIMARY KEY table constraint for the table films.
+ PRIMARY KEY table constraints can be defined on one or more
+ columns of the table
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE films (
+ code CHAR(05),
+ title VARCHAR(40),
+ did DECIMAL(03),
+ date_prod DATE,
+ kind CHAR(10),
+ len INTERVAL HOUR TO MINUTE,
+ CONSTRAINT code_title PRIMARY KEY(code,title)
+ );
+ </ProgramListing>
+
+ <PARA>
+ Defines a PRIMARY KEY column constraint for table distributors.
+ PRIMARY KEY column constraints can only be defined on one column
+ of the table (the following two examples are equivalents)
+ </PARA>
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(03),
+ name CHAR VARYING(40),
+ PRIMARY KEY(did)
+ );
+
+ CREATE TABLE distributors (
+ did DECIMAL(03) PRIMARY KEY,
+ name VARCHAR(40)
+ );
+ </ProgramListing>
+ <para>
+ To assign a sequence as the default for the column did,
+ and a literal to the column name
+ </PARA>
+
+ <ProgramListing>
+ CREATE TABLE distributors (
+ did DECIMAL(3) DEFAULT NEXTVAL('serial'),
+ name VARCHAR(40) DEFAULT 'luso films'
+ );
+ </ProgramListing>
+
+ <REFSECT2 ID="R2-SQL-CREATETABLE-3">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ Notes
+ </TITLE>
+ <PARA>
+ CREATE TABLE/INHERITS is a PostgreSQL language extension.
+ </PARA>
+ </refsect2>
+
+ </REFSECT1>
+
+ <REFSECT1 ID="R1-SQL-CREATETABLE-3">
+ <TITLE>
+ Compatibility
+ </TITLE>
+ <PARA>
+ </PARA>
+
+ <REFSECT2 ID="R2-SQL-CREATETABLE-4">
+ <REFSECT2INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT2INFO>
+ <TITLE>
+ SQL92
+ </TITLE>
+ <PARA>
+ In addition to normal CREATE TABLE, SQL92 also supports a
+ CREATE TEMPORARY TABLE statement.
+ </PARA>
+ <synopsis>
+ CREATE [ {GLOBAL | LOCAL} ] TEMPORARY TABLE table (
+ column type [DEFAULT value] [CONSTRAINT column_constraint] [, ...] )
+ [CONSTRAINT table_constraint ]
+ [ ON COMMIT {DELETE | PRESERVE} ROWS ]
+ </synopsis>
+ <para>
+ For temporary tables, the CREATE TEMPORARY TABLE statement
+ names a new table and defines the table's columns and
+ constraints.
+ </para>
+ <para>
+ The optional ON COMMIT clause of CREATE TEMPORARY TABLE
+ specifies whether or not the temporary table should be emptied of
+ rows whenever COMMIT is executed. If the ON COMMIT clause is
+ omitted, the default option, ON COMMIT DELETE ROWS, is assumed.
+ </para>
+ <para>
+ To create a temporary table:
+ </para>
+ <programlisting>
+ CREATE TEMPORARY TABLE actors (
+ id DECIMAL(03),
+ name VARCHAR(40),
+ CONSTRAINT actor_id CHECK (id < 150)
+ ) ON COMMIT DELETE ROWS
+ </programlisting>
+ <para>
+ TIP: In the current release of PostgreSQL (6.3.2), to create a temporary
+ table you must create and drop the table by explicit commands.
+ </para>
+
+ <REFSECT3 ID="R3-SQL-UNIQUECLAUSE-1">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ UNIQUE clause
+ </TITLE>
+ <PARA>
+ SQL92 specifies some additional capabilities for UNIQUE:
+ Table Constraint definition
+ </PARA>
+ <synopsis>
+ [ CONSTRAINT name ]
+ UNIQUE ( column [, ...] )
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ Column Constraint definition
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ UNIQUE
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ </refsect3>
+
+ <REFSECT3 ID="R3-SQL-NOTNULL-4">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ NOT NULL clause
+ </TITLE>
+ <PARA>
+
+ SQL92 specifies some additional capabilities for NOT NULL:
+ </PARA>
+ <synopsis>
+ [ CONSTRAINT name ] NOT NULL
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ </REFSECT3>
+
+ <REFSECT3 ID="R3-SQL-DEFAULTCLAUSE-1">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ DEFAULT clause
+ </TITLE>
+ <PARA>
+ SQL92 specifies some additional capabilities for the DEFAULT clause.
+ A DEFAULT clause is used to set the default value for a column
+ or a domain.
+ </para>
+ <synopsis>
+ DEFAULT <replaceable class="parameter">literal</replaceable> |
+ niladic USER function |
+ niladic datetime function |
+ NULL
+ </synopsis>
+ </refsect3>
+
+ <REFSECT3 ID="R3-SQL-CONSTRAINT-3">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ CONSTRAINT clause
+ </TITLE>
+ <PARA>
+ SQL92 specifies some additional capabilities for CONSTRAINTs,
+ it also defines assertions and domain constraints.
+ </PARA>
+ <PARA>
+ An assertion is a special type of integrity constraint and share
+ the same namespace as other constraints.
+ However, an assertion is not necessarily dependent on one
+ particular base table as constraints are, so SQL-92 provides the
+ CREATE ASSERTION statement as an alternate method for defining a
+ constraint:
+ </para>
+ <synopsis>
+ CREATE ASSERTION name CHECK ( condition )
+ </synopsis>
+
+ <PARA>
+ Domain constraints are defined by CREATE DOMAIN or ALTER DOMAIN
+ statements:
+ </para>
+ <PARA>
+ Domain constraint:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ CHECK constraint
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ Table constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ { PRIMARY KEY constraint |
+ FOREIGN KEY constraint |
+ UNIQUE constraint |
+ CHECK constraint }
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]</synopsis>
+ <para>
+ Column constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ { NOT NULL constraint |
+ PRIMARY KEY constraint |
+ FOREIGN KEY constraint |
+ UNIQUE constraint |
+ CHECK constraint }
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ A CONSTRAINT definition may contain one deferment attribute
+ clause and/or one initial constraint mode clause, in any order.
+ <variablelist>
+ <varlistentry>
+ <term>NOT DEFERRABLE</term>
+ <listitem>
+ <para>
+ means that the Constraint must be checked for
+ violation of its rule after the execution of every SQL statement.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>DEFERRABLE</term>
+ <listitem>
+ <para>
+ means that checking of the Constraint may be deferred
+ until some later time, but no later than the end of the current
+ transaction.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ <para>
+ The constraint mode for every Constraint always has an initial
+ default value which is set for that Constraint at the beginning
+ of a transaction.
+ <variablelist>
+ <varlistentry>
+ <term>INITIALLY IMMEDIATE</term>
+ <listitem>
+ <para>
+ means that, as of the start of the transaction,
+ the Constraint must be checked for violation of its rule after the
+ execution of every SQL statement.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>INITIALLY DEFERRED</term>
+ <listitem>
+ <para>
+ means that, as of the start of the transaction,
+ checking of the Constraint may be deferred until some later time,
+ but no later than the end of the current transaction.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ </refsect3>
+
+
+ <REFSECT3 ID="R3-SQL-CHECK-4">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ CHECK clause
+ </TITLE>
+ <PARA>
+ SQL92 specifies some additional capabilities for CHECK:
+ </PARA>
+ <para>
+ A CHECK constraint is either a table constraint, a column
+ constraint or a domain constraint.
+ </para>
+ <para>
+ table constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ CHECK ( VALUE condition )
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ column constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ CHECK ( VALUE condition )
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ domain constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ CHECK ( VALUE condition )
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ CHECK domain constraints can be defined in either
+ a CREATE DOMAIN statement or an ALTER DOMAIN statement:
+ </para>
+ <programlisting>
+ CREATE DOMAIN duration AS SMALLINT
+ CONSTRAINT minutes CHECK (VALUE IN (90,120,180,240));
+
+ ALTER DOMAIN cities
+ ADD CONSTRAINT new_city CHECK (VALUE LIKE 'L%');
+ </programlisting>
+ </refsect3>
+
+
+ <REFSECT3 ID="R3-SQL-PRIMARYKEY-1">
+ <REFSECT3INFO>
+ <DATE>1998-04-15</DATE>
+ </REFSECT3INFO>
+ <TITLE>
+ PRIMARY KEY clause
+ </TITLE>
+ <PARA>
+ SQL92 specifies some additional capabilities for PRIMARY KEY:
+ </para>
+ <PARA>
+ Table Constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ PRIMARY KEY ( column [, ...] )
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ <para>
+ Column Constraint definition:
+ </para>
+ <synopsis>
+ [ CONSTRAINT name ]
+ PRIMARY KEY
+ [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
+ [ [ NOT ] DEFERRABLE ]
+ </synopsis>
+ </refsect3>
+ </refsect2>
+ </refsect1>
+</refentry>
+
+<!-- Keep this comment at the end of the file
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