<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.24 2001/03/17 18:08:14 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/Attic/plsql.sgml,v 2.25 2001/03/23 22:07:50 tgl Exp $
-->
<chapter id="plpgsql">
This function should probably be integrated into the core.
</comment>
- <para>
- The third function (that takes 4 parameters) is implemented in
- PL/Tcl but I plan on porting it to PL/pgSQL so in case we want to
- include it in OpenACS we don't need to require PL/Tcl. Plus
- PL/pgSQL should be more efficient.
- </para>
-
<programlisting>
--
-- instr functions that mimic Oracle's counterpart
-- not passed, assume 1 (search starts at first character).
--
-- by Roberto Mello (rmello@fslc.usu.edu)
+-- modified by Robert Gaszewski (graszew@poland.com)
-- Licensed under the GPL v2 or later.
--
-DROP FUNCTION instr(varchar, varchar);
-CREATE FUNCTION instr(varchar, varchar) RETURNS integer AS '
+DROP FUNCTION instr(varchar,varchar);
+CREATE FUNCTION instr(varchar,varchar) RETURNS integer AS '
DECLARE
pos integer;
BEGIN
- pos:= instr($1, $2, 1);
+ pos:= instr($1,$2,1);
RETURN pos;
END;
-' LANGUAGE 'plpgsql';
+' language 'plpgsql';
+
+
+DROP FUNCTION instr(varchar,varchar,integer);
+CREATE FUNCTION instr(varchar,varchar,integer) RETURNS integer AS '
+DECLARE
+ string ALIAS FOR $1;
+ string_to_search ALIAS FOR $2;
+ beg_index ALIAS FOR $3;
+ pos integer NOT NULL DEFAULT 0;
+ temp_str varchar;
+ beg integer;
+ length integer;
+ ss_length integer;
+BEGIN
+ IF beg_index > 0 THEN
+
+ temp_str := substring(string FROM beg_index);
+ pos := position(string_to_search IN temp_str);
+
+ IF pos = 0 THEN
+ RETURN 0;
+ ELSE
+ RETURN pos + beg_index - 1;
+ END IF;
+ ELSE
+ ss_length := char_length(string_to_search);
+ length := char_length(string);
+ beg := length + beg_index - ss_length + 2;
+
+ WHILE beg > 0 LOOP
+
+ temp_str := substring(string FROM beg FOR ss_length);
+ pos := position(string_to_search IN temp_str);
+
+ IF pos > 0 THEN
+ RETURN beg;
+ END IF;
+
+ beg := beg - 1;
+ END LOOP;
+ RETURN 0;
+ END IF;
+END;
+' language 'plpgsql';
-DROP FUNCTION instr(varchar, varchar, integer);
-CREATE FUNCTION instr(varchar, varchar, integer) RETURNS integer AS '
+--
+-- Written by Robert Gaszewski (graszew@poland.com)
+-- Licensed under the GPL v2 or later.
+--
+DROP FUNCTION instr(varchar,varchar,integer,integer);
+CREATE FUNCTION instr(varchar,varchar,integer,integer) RETURNS integer AS '
DECLARE
string ALIAS FOR $1;
string_to_search ALIAS FOR $2;
beg_index ALIAS FOR $3;
+ occur_index ALIAS FOR $4;
pos integer NOT NULL DEFAULT 0;
- ending integer;
+ occur_number integer NOT NULL DEFAULT 0;
temp_str varchar;
beg integer;
+ i integer;
length integer;
- temp_int integer;
+ ss_length integer;
BEGIN
IF beg_index > 0 THEN
- -- Get substring from 1 to beg_index
+ beg := beg_index;
+ temp_str := substring(string FROM beg_index);
- temp_str := substring(string FROM beg_index);
- pos := position(string_to_search IN temp_str);
+ FOR i IN 1..occur_index LOOP
+ pos := position(string_to_search IN temp_str);
+
+ IF i = 1 THEN
+ beg := beg + pos - 1;
+ ELSE
+ beg := beg + pos;
+ END IF;
+
+ temp_str := substring(string FROM beg + 1);
+ END LOOP;
IF pos = 0 THEN
RETURN 0;
ELSE
- RETURN pos + beg_index - 1;
+ RETURN beg;
END IF;
-
ELSE
+ ss_length := char_length(string_to_search);
length := char_length(string);
+ beg := length + beg_index - ss_length + 2;
- IF beg_index = -1 THEN
- ending := length;
- beg := ending;
- temp_int := 1;
- ELSE
- ending := length - abs(beg_index);
- beg := ending;
- temp_int := ending - beg;
- END IF;
-
- WHILE pos = 0 AND beg <> 1 LOOP
-
- temp_str := substring(string FROM beg FOR temp_int);
+ WHILE beg > 0 LOOP
+ temp_str := substring(string FROM beg FOR ss_length);
pos := position(string_to_search IN temp_str);
- -- Keep moving left
+ IF pos > 0 THEN
+ occur_number := occur_number + 1;
+
+ IF occur_number = occur_index THEN
+ RETURN beg;
+ END IF;
+ END IF;
beg := beg - 1;
- temp_int := (ending - beg) + 1;
END LOOP;
- END IF;
- IF pos = 0 THEN
RETURN 0;
- ELSE
- RETURN beg + 1;
END IF;
END;
-' LANGUAGE 'plpgsql';
-
---
--- The next one (where all four params are passed) is in PL/Tcl
--- because I had no more patience to do it in PL/pgSQL.
--- It'd probably be faster in PL/pgSQL (that being the reason why
--- I implemented the first two functions in PL/pgSQL) so someday I'll do it.
---
-
-DROP FUNCTION instr(varchar, varchar, integer, integer);
-CREATE FUNCTION instr(varchar, varchar, integer, integer) RETURNS integer AS '
- set string1 $1
- set string2 $2
- set n $3
- set m $4
-
- if { $n > 0 } {
- set pos [string first $string2 $string1 [expr $n -1]]
- if { $pos < 0 } {
- return 0
- } else {
- for { set i 1 } { $i < $m } { incr i } {
- set pos [string first $string2 $string1 [expr $pos + 1]]
- if { $pos < 0 } {
- return 0
- }
- }
- }
- }
-
- if { $n < 0 } {
- set pos [string last $string2 $string1 [expr [string length $string1] + $n]]
-
- if { $pos < 0 } {
- return 0
- } else {
- for { set i 1 } { $i < $m } { incr i } {
- # n is negative so we add
- set pos [string last $string2 $string1 [expr $pos - 1]]
- if { $pos < 0 } {
- return 0
- }
- }
- }
- }
-
- if { $pos < 0 } {
- return 0
- } else {
- return [expr $pos + 1]
- }
-' LANGUAGE 'pltcl';
+' language 'plpgsql';
</programlisting>
</sect3>
</sect2>
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