<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.39 2006/09/02 20:34:47 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/update.sgml,v 1.40 2006/09/03 22:37:05 tgl Exp $
PostgreSQL documentation
-->
<refsynopsisdiv>
<synopsis>
UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
- [ SET <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] |
- SET ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] ]
+ SET { <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } |
+ ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) } [, ...]
[ FROM <replaceable class="PARAMETER">fromlist</replaceable> ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ AS <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
UPDATE weather SET temp_lo = temp_lo+1, temp_hi = temp_lo+15, prcp = DEFAULT
WHERE city = 'San Francisco' AND date = '2003-07-03';
</programlisting>
-<programlisting>
-UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
- WHERE city = 'San Francisco' AND date = '2003-07-03';
-</programlisting>
</para>
<para>
</para>
<para>
+ Use the alternative column-list syntax to do the same update:
+<programlisting>
+UPDATE weather SET (temp_lo, temp_hi, prcp) = (temp_lo+1, temp_lo+15, DEFAULT)
+ WHERE city = 'San Francisco' AND date = '2003-07-03';
+</programlisting>
+ </para>
+
+ <para>
Increment the sales count of the salesperson who manages the
account for Acme Corporation, using the <literal>FROM</literal>
clause syntax:
</para>
<para>
+ According to the standard, the column-list syntax should allow a list
+ of columns to be assigned from a single row-valued expression, such
+ as a sub-select:
+<programlisting>
+UPDATE accounts SET (contact_last_name, contact_first_name) =
+ (SELECT last_name, first_name FROM salesmen
+ WHERE salesmen.id = accounts.sales_id);
+</programlisting>
+ This is not currently implemented — the source must be a list
+ of independent expressions.
+ </para>
+
+ <para>
Some other database systems offer a <literal>FROM</> option in which
the target table is supposed to be listed again within <literal>FROM</>.
That is not how <productname>PostgreSQL</productname> interprets
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.564 2006/09/03 03:19:44 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.565 2006/09/03 22:37:05 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
name_list from_clause from_list opt_array_bounds
qualified_name_list any_name any_name_list
any_operator expr_list attrs
- target_list update_col_list update_target_list
- update_value_list set_opt insert_column_list
- values_list def_list indirection opt_indirection
+ target_list insert_column_list set_target_list
+ set_clause_list set_clause multiple_set_clause
+ ctext_expr_list ctext_row def_list indirection opt_indirection
group_clause TriggerFuncArgs select_limit
opt_select_limit opclass_item_list
transaction_mode_list_or_empty
%type <list> when_clause_list
%type <ival> sub_type
%type <list> OptCreateAs CreateAsList
-%type <node> CreateAsElement values_item
+%type <node> CreateAsElement ctext_expr
%type <value> NumericOnly FloatOnly IntegerOnly
%type <alias> alias_clause
%type <sortby> sortby
%type <jexpr> joined_table
%type <range> relation_expr
%type <range> relation_expr_opt_alias
-%type <target> target_el update_target_el update_col_list_el insert_column_item
-%type <list> update_target_lists_list update_target_lists_el
+%type <target> target_el single_set_clause set_target insert_column_item
%type <typnam> Typename SimpleTypename ConstTypename
GenericType Numeric opt_float
*****************************************************************************/
UpdateStmt: UPDATE relation_expr_opt_alias
- SET set_opt
+ SET set_clause_list
from_clause
where_clause
returning_clause
}
;
-set_opt:
- update_target_list { $$ = $1; }
- | update_target_lists_list { $$ = $1; }
+set_clause_list:
+ set_clause { $$ = $1; }
+ | set_clause_list ',' set_clause { $$ = list_concat($1,$3); }
+ ;
+
+set_clause:
+ single_set_clause { $$ = list_make1($1); }
+ | multiple_set_clause { $$ = $1; }
+ ;
+
+single_set_clause:
+ set_target '=' ctext_expr
+ {
+ $$ = $1;
+ $$->val = (Node *) $3;
+ }
+ ;
+
+multiple_set_clause:
+ '(' set_target_list ')' '=' ctext_row
+ {
+ ListCell *col_cell;
+ ListCell *val_cell;
+
+ /*
+ * Break the ctext_row apart, merge individual expressions
+ * into the destination ResTargets. XXX this approach
+ * cannot work for general row expressions as sources.
+ */
+ if (list_length($2) != list_length($5))
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("number of columns does not match number of values")));
+ forboth(col_cell, $2, val_cell, $5)
+ {
+ ResTarget *res_col = (ResTarget *) lfirst(col_cell);
+ Node *res_val = (Node *) lfirst(val_cell);
+
+ res_col->val = res_val;
+ }
+
+ $$ = $2;
+ }
+ ;
+
+set_target:
+ ColId opt_indirection
+ {
+ $$ = makeNode(ResTarget);
+ $$->name = $1;
+ $$->indirection = $2;
+ $$->val = NULL; /* upper production sets this */
+ $$->location = @1;
+ }
+ ;
+
+set_target_list:
+ set_target { $$ = list_make1($1); }
+ | set_target_list ',' set_target { $$ = lappend($1,$3); }
;
values_clause:
- VALUES '(' values_list ')'
+ VALUES ctext_row
{
SelectStmt *n = makeNode(SelectStmt);
- n->valuesLists = list_make1($3);
+ n->valuesLists = list_make1($2);
$$ = (Node *) n;
}
- | values_clause ',' '(' values_list ')'
+ | values_clause ',' ctext_row
{
SelectStmt *n = (SelectStmt *) $1;
- n->valuesLists = lappend(n->valuesLists, $4);
+ n->valuesLists = lappend(n->valuesLists, $3);
$$ = (Node *) n;
}
;
-values_list: values_item { $$ = list_make1($1); }
- | values_list ',' values_item { $$ = lappend($1, $3); }
- ;
-
-values_item:
- a_expr { $$ = (Node *) $1; }
- | DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
- ;
-
-update_target_lists_list:
- update_target_lists_el { $$ = $1; }
- | update_target_lists_list ',' update_target_lists_el { $$ = list_concat($1, $3); }
- ;
-
-update_target_lists_el:
- '(' update_col_list ')' '=' '(' update_value_list ')'
- {
- ListCell *col_cell;
- ListCell *val_cell;
-
- if (list_length($2) != list_length($6))
- {
- ereport(ERROR,
- (errcode(ERRCODE_SYNTAX_ERROR),
- errmsg("number of columns does not match to number of values")));
- }
-
- for (col_cell = list_head($2), val_cell = list_head($6);
- col_cell != NULL && val_cell != NULL;
- col_cell = lnext(col_cell), val_cell = lnext(val_cell))
- {
- /* merge update_value_list with update_col_list */
- ResTarget *res_col = (ResTarget *) lfirst(col_cell);
- Node *res_val = (Node *) lfirst(val_cell);
-
- res_col->val = res_val;
- }
-
- $$ = $2;
- }
- ;
-
-update_col_list:
- update_col_list_el { $$ = list_make1($1); }
- | update_col_list ',' update_col_list_el { $$ = lappend($1, $3); }
- ;
-
-update_col_list_el:
- ColId opt_indirection
- {
- $$ = makeNode(ResTarget);
- $$->name = $1;
- $$->indirection = $2;
- $$->val = NULL;
- $$->location = @1;
- }
- ;
-
-update_value_list:
- values_item { $$ = list_make1($1); }
- | update_value_list ',' values_item { $$ = lappend($1, $3); }
- ;
-
/*****************************************************************************
*
| /*EMPTY*/
;
+/*
+ * The SQL spec defines "contextually typed value expressions" and
+ * "contextually typed row value constructors", which for our purposes
+ * are the same as "a_expr" and "row" except that DEFAULT can appear at
+ * the top level.
+ */
+
+ctext_expr:
+ a_expr { $$ = (Node *) $1; }
+ | DEFAULT { $$ = (Node *) makeNode(SetToDefault); }
+ ;
+
+ctext_expr_list:
+ ctext_expr { $$ = list_make1($1); }
+ | ctext_expr_list ',' ctext_expr { $$ = lappend($1, $3); }
+ ;
+
+/*
+ * We should allow ROW '(' ctext_expr_list ')' too, but that seems to require
+ * making VALUES a fully reserved word, which will probably break more apps
+ * than allowing the noise-word is worth.
+ */
+ctext_row: '(' ctext_expr_list ')' { $$ = $2; }
+ ;
+
/*****************************************************************************
*
- * target lists for SELECT, UPDATE, INSERT
+ * target list for SELECT
*
*****************************************************************************/
}
;
-update_target_list:
- update_target_el { $$ = list_make1($1); }
- | update_target_list ',' update_target_el { $$ = lappend($1,$3); }
- ;
-
-update_target_el:
- ColId opt_indirection '=' a_expr
- {
- $$ = makeNode(ResTarget);
- $$->name = $1;
- $$->indirection = $2;
- $$->val = (Node *) $4;
- $$->location = @1;
- }
- | ColId opt_indirection '=' DEFAULT
- {
- $$ = makeNode(ResTarget);
- $$->name = $1;
- $$->indirection = $2;
- $$->val = (Node *) makeNode(SetToDefault);
- $$->location = @1;
- }
-
- ;
-
/*****************************************************************************
*
--
--- UPDATE ... SET <col> = DEFAULT;
+-- UPDATE syntax tests
--
CREATE TABLE update_test (
a INT DEFAULT 10,
- b INT
+ b INT,
+ c TEXT
);
-INSERT INTO update_test VALUES (5, 10);
-INSERT INTO update_test VALUES (10, 15);
+INSERT INTO update_test VALUES (5, 10, 'foo');
+INSERT INTO update_test(b, a) VALUES (15, 10);
SELECT * FROM update_test;
- a | b
-----+----
- 5 | 10
- 10 | 15
+ a | b | c
+----+----+-----
+ 5 | 10 | foo
+ 10 | 15 |
(2 rows)
UPDATE update_test SET a = DEFAULT, b = DEFAULT;
SELECT * FROM update_test;
- a | b
-----+---
- 10 |
- 10 |
+ a | b | c
+----+---+-----
+ 10 | | foo
+ 10 | |
(2 rows)
-- aliases for the UPDATE target table
UPDATE update_test AS t SET b = 10 WHERE t.a = 10;
SELECT * FROM update_test;
- a | b
-----+----
- 10 | 10
- 10 | 10
+ a | b | c
+----+----+-----
+ 10 | 10 | foo
+ 10 | 10 |
(2 rows)
UPDATE update_test t SET b = t.b + 10 WHERE t.a = 10;
SELECT * FROM update_test;
- a | b
-----+----
- 10 | 20
- 10 | 20
+ a | b | c
+----+----+-----
+ 10 | 20 | foo
+ 10 | 20 |
(2 rows)
--
-- Test VALUES in FROM
--
UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
- WHERE update_test.b = v.j;
+ WHERE update_test.b = v.j;
SELECT * FROM update_test;
- a | b
------+----
- 100 | 20
- 100 | 20
+ a | b | c
+-----+----+-----
+ 100 | 20 | foo
+ 100 | 20 |
(2 rows)
+--
+-- Test multiple-set-clause syntax
+--
+UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
+SELECT * FROM update_test;
+ a | b | c
+-----+----+-------
+ 100 | 20 |
+ 10 | 31 | bugle
+(2 rows)
+
+UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
+SELECT * FROM update_test;
+ a | b | c
+-----+----+-----
+ 100 | 20 |
+ 11 | 41 | car
+(2 rows)
+
+-- fail, multi assignment to same column:
+UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
+ERROR: multiple assignments to same column "b"
+-- XXX this should work, but doesn't yet:
+UPDATE update_test SET (a,b) = (select a,b FROM update_test where c = 'foo')
+ WHERE a = 10;
+ERROR: syntax error at or near "select"
+LINE 1: UPDATE update_test SET (a,b) = (select a,b FROM update_test ...
+ ^
-- if an alias for the target table is specified, don't allow references
-- to the original table name
BEGIN;
--
--- UPDATE ... SET <col> = DEFAULT;
+-- UPDATE syntax tests
--
CREATE TABLE update_test (
a INT DEFAULT 10,
- b INT
+ b INT,
+ c TEXT
);
-INSERT INTO update_test VALUES (5, 10);
-INSERT INTO update_test VALUES (10, 15);
+INSERT INTO update_test VALUES (5, 10, 'foo');
+INSERT INTO update_test(b, a) VALUES (15, 10);
SELECT * FROM update_test;
--
UPDATE update_test SET a=v.i FROM (VALUES(100, 20)) AS v(i, j)
- WHERE update_test.b = v.j;
+ WHERE update_test.b = v.j;
SELECT * FROM update_test;
+--
+-- Test multiple-set-clause syntax
+--
+
+UPDATE update_test SET (c,b,a) = ('bugle', b+11, DEFAULT) WHERE c = 'foo';
+SELECT * FROM update_test;
+UPDATE update_test SET (c,b) = ('car', a+b), a = a + 1 WHERE a = 10;
+SELECT * FROM update_test;
+-- fail, multi assignment to same column:
+UPDATE update_test SET (c,b) = ('car', a+b), b = a + 1 WHERE a = 10;
+
+-- XXX this should work, but doesn't yet:
+UPDATE update_test SET (a,b) = (select a,b FROM update_test where c = 'foo')
+ WHERE a = 10;
+
-- if an alias for the target table is specified, don't allow references
-- to the original table name
BEGIN;
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