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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>43.13. Porting from Oracle PL/SQL</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="plpgsql-development-tips.html" title="43.12. Tips for Developing in PL/pgSQL" /><link rel="next" href="pltcl.html" title="Chapter 44. PL/Tcl — Tcl Procedural Language" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">43.13. Porting from <span class="productname">Oracle</span> PL/SQL</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="plpgsql-development-tips.html" title="43.12. Tips for Developing in PL/pgSQL">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="plpgsql.html" title="Chapter 43. PL/pgSQL — SQL Procedural Language">Up</a></td><th width="60%" align="center">Chapter 43. <span class="application">PL/pgSQL</span> — <acronym class="acronym">SQL</acronym> Procedural Language</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="pltcl.html" title="Chapter 44. PL/Tcl — Tcl Procedural Language">Next</a></td></tr></table><hr /></div><div class="sect1" id="PLPGSQL-PORTING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">43.13. Porting from <span class="productname">Oracle</span> PL/SQL <a href="#PLPGSQL-PORTING" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="plpgsql-porting.html#PLPGSQL-PORTING-EXAMPLES">43.13.1. Porting Examples</a></span></dt><dt><span class="sect2"><a href="plpgsql-porting.html#PLPGSQL-PORTING-OTHER">43.13.2. Other Things to Watch For</a></span></dt><dt><span class="sect2"><a href="plpgsql-porting.html#PLPGSQL-PORTING-APPENDIX">43.13.3. Appendix</a></span></dt></dl></div><a id="id-1.8.8.15.2" class="indexterm"></a><a id="id-1.8.8.15.3" class="indexterm"></a><p>3 This section explains differences between4 <span class="productname">PostgreSQL</span>'s <span class="application">PL/pgSQL</span>5 language and Oracle's <span class="application">PL/SQL</span> language,6 to help developers who port applications from7 <span class="trademark">Oracle</span>® to <span class="productname">PostgreSQL</span>.8 </p><p>9 <span class="application">PL/pgSQL</span> is similar to PL/SQL in many10 aspects. It is a block-structured, imperative language, and all11 variables have to be declared. Assignments, loops, and conditionals12 are similar. The main differences you should keep in mind when13 porting from <span class="application">PL/SQL</span> to14 <span class="application">PL/pgSQL</span> are:15 16 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>17 If a name used in an SQL command could be either a column name of a18 table used in the command or a reference to a variable of the function,19 <span class="application">PL/SQL</span> treats it as a column name.20 By default, <span class="application">PL/pgSQL</span> will throw an error21 complaining that the name is ambiguous. You can specify22 <code class="literal">plpgsql.variable_conflict</code> = <code class="literal">use_column</code>23 to change this behavior to match <span class="application">PL/SQL</span>,24 as explained in <a class="xref" href="plpgsql-implementation.html#PLPGSQL-VAR-SUBST" title="43.11.1. Variable Substitution">Section 43.11.1</a>.25 It's often best to avoid such ambiguities in the first place,26 but if you have to port a large amount of code that depends on27 this behavior, setting <code class="literal">variable_conflict</code> may be the28 best solution.29 </p></li><li class="listitem"><p>30 In <span class="productname">PostgreSQL</span> the function body must be written as31 a string literal. Therefore you need to use dollar quoting or escape32 single quotes in the function body. (See <a class="xref" href="plpgsql-development-tips.html#PLPGSQL-QUOTE-TIPS" title="43.12.1. Handling of Quotation Marks">Section 43.12.1</a>.)33 </p></li><li class="listitem"><p>34 Data type names often need translation. For example, in Oracle string35 values are commonly declared as being of type <code class="type">varchar2</code>, which36 is a non-SQL-standard type. In <span class="productname">PostgreSQL</span>,37 use type <code class="type">varchar</code> or <code class="type">text</code> instead. Similarly, replace38 type <code class="type">number</code> with <code class="type">numeric</code>, or use some other numeric39 data type if there's a more appropriate one.40 </p></li><li class="listitem"><p>41 Instead of packages, use schemas to organize your functions42 into groups.43 </p></li><li class="listitem"><p>44 Since there are no packages, there are no package-level variables45 either. This is somewhat annoying. You can keep per-session state46 in temporary tables instead.47 </p></li><li class="listitem"><p>48 Integer <code class="command">FOR</code> loops with <code class="literal">REVERSE</code> work49 differently: <span class="application">PL/SQL</span> counts down from the second50 number to the first, while <span class="application">PL/pgSQL</span> counts down51 from the first number to the second, requiring the loop bounds52 to be swapped when porting. This incompatibility is unfortunate53 but is unlikely to be changed. (See <a class="xref" href="plpgsql-control-structures.html#PLPGSQL-INTEGER-FOR" title="43.6.5.5. FOR (Integer Variant)">Section 43.6.5.5</a>.)54 </p></li><li class="listitem"><p>55 <code class="command">FOR</code> loops over queries (other than cursors) also work56 differently: the target variable(s) must have been declared,57 whereas <span class="application">PL/SQL</span> always declares them implicitly.58 An advantage of this is that the variable values are still accessible59 after the loop exits.60 </p></li><li class="listitem"><p>61 There are various notational differences for the use of cursor62 variables.63 </p></li></ul></div><p>64 </p><div class="sect2" id="PLPGSQL-PORTING-EXAMPLES"><div class="titlepage"><div><div><h3 class="title">43.13.1. Porting Examples <a href="#PLPGSQL-PORTING-EXAMPLES" class="id_link">#</a></h3></div></div></div><p>65 <a class="xref" href="plpgsql-porting.html#PGSQL-PORTING-EX1" title="Example 43.9. Porting a Simple Function from PL/SQL to PL/pgSQL">Example 43.9</a> shows how to port a simple66 function from <span class="application">PL/SQL</span> to <span class="application">PL/pgSQL</span>.67 </p><div class="example" id="PGSQL-PORTING-EX1"><p class="title"><strong>Example 43.9. Porting a Simple Function from <span class="application">PL/SQL</span> to <span class="application">PL/pgSQL</span></strong></p><div class="example-contents"><p>68 Here is an <span class="productname">Oracle</span> <span class="application">PL/SQL</span> function:69</p><pre class="programlisting">70CREATE OR REPLACE FUNCTION cs_fmt_browser_version(v_name varchar2,71 v_version varchar2)72RETURN varchar2 IS73BEGIN74 IF v_version IS NULL THEN75 RETURN v_name;76 END IF;77 RETURN v_name || '/' || v_version;78END;79/80show errors;81</pre><p>82 </p><p>83 Let's go through this function and see the differences compared to84 <span class="application">PL/pgSQL</span>:85 86 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>87 The type name <code class="type">varchar2</code> has to be changed to <code class="type">varchar</code>88 or <code class="type">text</code>. In the examples in this section, we'll89 use <code class="type">varchar</code>, but <code class="type">text</code> is often a better choice if90 you do not need specific string length limits.91 </p></li><li class="listitem"><p>92 The <code class="literal">RETURN</code> key word in the function93 prototype (not the function body) becomes94 <code class="literal">RETURNS</code> in95 <span class="productname">PostgreSQL</span>.96 Also, <code class="literal">IS</code> becomes <code class="literal">AS</code>, and you need to97 add a <code class="literal">LANGUAGE</code> clause because <span class="application">PL/pgSQL</span>98 is not the only possible function language.99 </p></li><li class="listitem"><p>100 In <span class="productname">PostgreSQL</span>, the function body is considered101 to be a string literal, so you need to use quote marks or dollar102 quotes around it. This substitutes for the terminating <code class="literal">/</code>103 in the Oracle approach.104 </p></li><li class="listitem"><p>105 The <code class="literal">show errors</code> command does not exist in106 <span class="productname">PostgreSQL</span>, and is not needed since errors are107 reported automatically.108 </p></li></ul></div><p>109 </p><p>110 This is how this function would look when ported to111 <span class="productname">PostgreSQL</span>:112 113</p><pre class="programlisting">114CREATE OR REPLACE FUNCTION cs_fmt_browser_version(v_name varchar,115 v_version varchar)116RETURNS varchar AS $$117BEGIN118 IF v_version IS NULL THEN119 RETURN v_name;120 END IF;121 RETURN v_name || '/' || v_version;122END;123$$ LANGUAGE plpgsql;124</pre><p>125 </p></div></div><br class="example-break" /><p>126 <a class="xref" href="plpgsql-porting.html#PLPGSQL-PORTING-EX2" title="Example 43.10. Porting a Function that Creates Another Function from PL/SQL to PL/pgSQL">Example 43.10</a> shows how to port a127 function that creates another function and how to handle the128 ensuing quoting problems.129 </p><div class="example" id="PLPGSQL-PORTING-EX2"><p class="title"><strong>Example 43.10. Porting a Function that Creates Another Function from <span class="application">PL/SQL</span> to <span class="application">PL/pgSQL</span></strong></p><div class="example-contents"><p>130 The following procedure grabs rows from a131 <code class="command">SELECT</code> statement and builds a large function132 with the results in <code class="literal">IF</code> statements, for the133 sake of efficiency.134 </p><p>135 This is the Oracle version:136</p><pre class="programlisting">137CREATE OR REPLACE PROCEDURE cs_update_referrer_type_proc IS138 CURSOR referrer_keys IS139 SELECT * FROM cs_referrer_keys140 ORDER BY try_order;141 func_cmd VARCHAR(4000);142BEGIN143 func_cmd := 'CREATE OR REPLACE FUNCTION cs_find_referrer_type(v_host IN VARCHAR2,144 v_domain IN VARCHAR2, v_url IN VARCHAR2) RETURN VARCHAR2 IS BEGIN';145 146 FOR referrer_key IN referrer_keys LOOP147 func_cmd := func_cmd ||148 ' IF v_' || referrer_key.kind149 || ' LIKE ''' || referrer_key.key_string150 || ''' THEN RETURN ''' || referrer_key.referrer_type151 || '''; END IF;';152 END LOOP;153 154 func_cmd := func_cmd || ' RETURN NULL; END;';155 156 EXECUTE IMMEDIATE func_cmd;157END;158/159show errors;160</pre><p>161 </p><p>162 Here is how this function would end up in <span class="productname">PostgreSQL</span>:163</p><pre class="programlisting">164CREATE OR REPLACE PROCEDURE cs_update_referrer_type_proc() AS $func$165DECLARE166 referrer_keys CURSOR IS167 SELECT * FROM cs_referrer_keys168 ORDER BY try_order;169 func_body text;170 func_cmd text;171BEGIN172 func_body := 'BEGIN';173 174 FOR referrer_key IN referrer_keys LOOP175 func_body := func_body ||176 ' IF v_' || referrer_key.kind177 || ' LIKE ' || quote_literal(referrer_key.key_string)178 || ' THEN RETURN ' || quote_literal(referrer_key.referrer_type)179 || '; END IF;' ;180 END LOOP;181 182 func_body := func_body || ' RETURN NULL; END;';183 184 func_cmd :=185 'CREATE OR REPLACE FUNCTION cs_find_referrer_type(v_host varchar,186 v_domain varchar,187 v_url varchar)188 RETURNS varchar AS '189 || quote_literal(func_body)190 || ' LANGUAGE plpgsql;' ;191 192 EXECUTE func_cmd;193END;194$func$ LANGUAGE plpgsql;195</pre><p>196 Notice how the body of the function is built separately and passed197 through <code class="literal">quote_literal</code> to double any quote marks in it. This198 technique is needed because we cannot safely use dollar quoting for199 defining the new function: we do not know for sure what strings will200 be interpolated from the <code class="structfield">referrer_key.key_string</code> field.201 (We are assuming here that <code class="structfield">referrer_key.kind</code> can be202 trusted to always be <code class="literal">host</code>, <code class="literal">domain</code>, or203 <code class="literal">url</code>, but <code class="structfield">referrer_key.key_string</code> might be204 anything, in particular it might contain dollar signs.) This function205 is actually an improvement on the Oracle original, because it will206 not generate broken code when <code class="structfield">referrer_key.key_string</code> or207 <code class="structfield">referrer_key.referrer_type</code> contain quote marks.208 </p></div></div><br class="example-break" /><p>209 <a class="xref" href="plpgsql-porting.html#PLPGSQL-PORTING-EX3" title="Example 43.11. Porting a Procedure With String Manipulation and OUT Parameters from PL/SQL to PL/pgSQL">Example 43.11</a> shows how to port a function210 with <code class="literal">OUT</code> parameters and string manipulation.211 <span class="productname">PostgreSQL</span> does not have a built-in212 <code class="function">instr</code> function, but you can create one213 using a combination of other214 functions. In <a class="xref" href="plpgsql-porting.html#PLPGSQL-PORTING-APPENDIX" title="43.13.3. Appendix">Section 43.13.3</a> there is a215 <span class="application">PL/pgSQL</span> implementation of216 <code class="function">instr</code> that you can use to make your porting217 easier.218 </p><div class="example" id="PLPGSQL-PORTING-EX3"><p class="title"><strong>Example 43.11. Porting a Procedure With String Manipulation and219 <code class="literal">OUT</code> Parameters from <span class="application">PL/SQL</span> to220 <span class="application">PL/pgSQL</span></strong></p><div class="example-contents"><p>221 The following <span class="productname">Oracle</span> PL/SQL procedure is used222 to parse a URL and return several elements (host, path, and query).223 </p><p>224 This is the Oracle version:225</p><pre class="programlisting">226CREATE OR REPLACE PROCEDURE cs_parse_url(227 v_url IN VARCHAR2,228 v_host OUT VARCHAR2, -- This will be passed back229 v_path OUT VARCHAR2, -- This one too230 v_query OUT VARCHAR2) -- And this one231IS232 a_pos1 INTEGER;233 a_pos2 INTEGER;234BEGIN235 v_host := NULL;236 v_path := NULL;237 v_query := NULL;238 a_pos1 := instr(v_url, '//');239 240 IF a_pos1 = 0 THEN241 RETURN;242 END IF;243 a_pos2 := instr(v_url, '/', a_pos1 + 2);244 IF a_pos2 = 0 THEN245 v_host := substr(v_url, a_pos1 + 2);246 v_path := '/';247 RETURN;248 END IF;249 250 v_host := substr(v_url, a_pos1 + 2, a_pos2 - a_pos1 - 2);251 a_pos1 := instr(v_url, '?', a_pos2 + 1);252 253 IF a_pos1 = 0 THEN254 v_path := substr(v_url, a_pos2);255 RETURN;256 END IF;257 258 v_path := substr(v_url, a_pos2, a_pos1 - a_pos2);259 v_query := substr(v_url, a_pos1 + 1);260END;261/262show errors;263</pre><p>264 </p><p>265 Here is a possible translation into <span class="application">PL/pgSQL</span>:266</p><pre class="programlisting">267CREATE OR REPLACE FUNCTION cs_parse_url(268 v_url IN VARCHAR,269 v_host OUT VARCHAR, -- This will be passed back270 v_path OUT VARCHAR, -- This one too271 v_query OUT VARCHAR) -- And this one272AS $$273DECLARE274 a_pos1 INTEGER;275 a_pos2 INTEGER;276BEGIN277 v_host := NULL;278 v_path := NULL;279 v_query := NULL;280 a_pos1 := instr(v_url, '//');281 282 IF a_pos1 = 0 THEN283 RETURN;284 END IF;285 a_pos2 := instr(v_url, '/', a_pos1 + 2);286 IF a_pos2 = 0 THEN287 v_host := substr(v_url, a_pos1 + 2);288 v_path := '/';289 RETURN;290 END IF;291 292 v_host := substr(v_url, a_pos1 + 2, a_pos2 - a_pos1 - 2);293 a_pos1 := instr(v_url, '?', a_pos2 + 1);294 295 IF a_pos1 = 0 THEN296 v_path := substr(v_url, a_pos2);297 RETURN;298 END IF;299 300 v_path := substr(v_url, a_pos2, a_pos1 - a_pos2);301 v_query := substr(v_url, a_pos1 + 1);302END;303$$ LANGUAGE plpgsql;304</pre><p>305 306 This function could be used like this:307</p><pre class="programlisting">308SELECT * FROM cs_parse_url('http://foobar.com/query.cgi?baz');309</pre><p>310 </p></div></div><br class="example-break" /><p>311 <a class="xref" href="plpgsql-porting.html#PLPGSQL-PORTING-EX4" title="Example 43.12. Porting a Procedure from PL/SQL to PL/pgSQL">Example 43.12</a> shows how to port a procedure312 that uses numerous features that are specific to Oracle.313 </p><div class="example" id="PLPGSQL-PORTING-EX4"><p class="title"><strong>Example 43.12. Porting a Procedure from <span class="application">PL/SQL</span> to <span class="application">PL/pgSQL</span></strong></p><div class="example-contents"><p>314 The Oracle version:315 316</p><pre class="programlisting">317CREATE OR REPLACE PROCEDURE cs_create_job(v_job_id IN INTEGER) IS318 a_running_job_count INTEGER;319BEGIN320 LOCK TABLE cs_jobs IN EXCLUSIVE MODE;321 322 SELECT count(*) INTO a_running_job_count FROM cs_jobs WHERE end_stamp IS NULL;323 324 IF a_running_job_count > 0 THEN325 COMMIT; -- free lock326 raise_application_error(-20000,327 'Unable to create a new job: a job is currently running.');328 END IF;329 330 DELETE FROM cs_active_job;331 INSERT INTO cs_active_job(job_id) VALUES (v_job_id);332 333 BEGIN334 INSERT INTO cs_jobs (job_id, start_stamp) VALUES (v_job_id, now());335 EXCEPTION336 WHEN dup_val_on_index THEN NULL; -- don't worry if it already exists337 END;338 COMMIT;339END;340/341show errors342</pre><p>343 </p><p>344 This is how we could port this procedure to <span class="application">PL/pgSQL</span>:345 346</p><pre class="programlisting">347CREATE OR REPLACE PROCEDURE cs_create_job(v_job_id integer) AS $$348DECLARE349 a_running_job_count integer;350BEGIN351 LOCK TABLE cs_jobs IN EXCLUSIVE MODE;352 353 SELECT count(*) INTO a_running_job_count FROM cs_jobs WHERE end_stamp IS NULL;354 355 IF a_running_job_count > 0 THEN356 COMMIT; -- free lock357 RAISE EXCEPTION 'Unable to create a new job: a job is currently running'; -- <span id="co.plpgsql-porting-raise"></span>(1)358 END IF;359 360 DELETE FROM cs_active_job;361 INSERT INTO cs_active_job(job_id) VALUES (v_job_id);362 363 BEGIN364 INSERT INTO cs_jobs (job_id, start_stamp) VALUES (v_job_id, now());365 EXCEPTION366 WHEN unique_violation THEN -- <span id="co.plpgsql-porting-exception"></span>(2)367 -- don't worry if it already exists368 END;369 COMMIT;370END;371$$ LANGUAGE plpgsql;372</pre><p>373 374 </p><div class="calloutlist"><table border="0" summary="Callout list"><tr><td width="5%" valign="top" align="left"><p><a href="#co.plpgsql-porting-raise">(1)</a> </p></td><td valign="top" align="left"><p>375 The syntax of <code class="literal">RAISE</code> is considerably different from376 Oracle's statement, although the basic case <code class="literal">RAISE</code>377 <em class="replaceable"><code>exception_name</code></em> works378 similarly.379 </p></td></tr><tr><td width="5%" valign="top" align="left"><p><a href="#co.plpgsql-porting-exception">(2)</a> </p></td><td valign="top" align="left"><p>380 The exception names supported by <span class="application">PL/pgSQL</span> are381 different from Oracle's. The set of built-in exception names382 is much larger (see <a class="xref" href="errcodes-appendix.html" title="Appendix A. PostgreSQL Error Codes">Appendix A</a>). There383 is not currently a way to declare user-defined exception names,384 although you can throw user-chosen SQLSTATE values instead.385 </p></td></tr></table></div><p>386 </p></div></div><br class="example-break" /></div><div class="sect2" id="PLPGSQL-PORTING-OTHER"><div class="titlepage"><div><div><h3 class="title">43.13.2. Other Things to Watch For <a href="#PLPGSQL-PORTING-OTHER" class="id_link">#</a></h3></div></div></div><p>387 This section explains a few other things to watch for when porting388 Oracle <span class="application">PL/SQL</span> functions to389 <span class="productname">PostgreSQL</span>.390 </p><div class="sect3" id="PLPGSQL-PORTING-EXCEPTIONS"><div class="titlepage"><div><div><h4 class="title">43.13.2.1. Implicit Rollback after Exceptions <a href="#PLPGSQL-PORTING-EXCEPTIONS" class="id_link">#</a></h4></div></div></div><p>391 In <span class="application">PL/pgSQL</span>, when an exception is caught by an392 <code class="literal">EXCEPTION</code> clause, all database changes since the block's393 <code class="literal">BEGIN</code> are automatically rolled back. That is, the behavior394 is equivalent to what you'd get in Oracle with:395 396</p><pre class="programlisting">397BEGIN398 SAVEPOINT s1;399 ... code here ...400EXCEPTION401 WHEN ... THEN402 ROLLBACK TO s1;403 ... code here ...404 WHEN ... THEN405 ROLLBACK TO s1;406 ... code here ...407END;408</pre><p>409 410 If you are translating an Oracle procedure that uses411 <code class="command">SAVEPOINT</code> and <code class="command">ROLLBACK TO</code> in this style,412 your task is easy: just omit the <code class="command">SAVEPOINT</code> and413 <code class="command">ROLLBACK TO</code>. If you have a procedure that uses414 <code class="command">SAVEPOINT</code> and <code class="command">ROLLBACK TO</code> in a different way415 then some actual thought will be required.416 </p></div><div class="sect3" id="PLPGSQL-PORTING-OTHER-EXECUTE"><div class="titlepage"><div><div><h4 class="title">43.13.2.2. <code class="command">EXECUTE</code> <a href="#PLPGSQL-PORTING-OTHER-EXECUTE" class="id_link">#</a></h4></div></div></div><p>417 The <span class="application">PL/pgSQL</span> version of418 <code class="command">EXECUTE</code> works similarly to the419 <span class="application">PL/SQL</span> version, but you have to remember to use420 <code class="function">quote_literal</code> and421 <code class="function">quote_ident</code> as described in <a class="xref" href="plpgsql-statements.html#PLPGSQL-STATEMENTS-EXECUTING-DYN" title="43.5.4. Executing Dynamic Commands">Section 43.5.4</a>. Constructs of the422 type <code class="literal">EXECUTE 'SELECT * FROM $1';</code> will not work423 reliably unless you use these functions.424 </p></div><div class="sect3" id="PLPGSQL-PORTING-OPTIMIZATION"><div class="titlepage"><div><div><h4 class="title">43.13.2.3. Optimizing <span class="application">PL/pgSQL</span> Functions <a href="#PLPGSQL-PORTING-OPTIMIZATION" class="id_link">#</a></h4></div></div></div><p>425 <span class="productname">PostgreSQL</span> gives you two function creation426 modifiers to optimize execution: <span class="quote">“<span class="quote">volatility</span>”</span> (whether427 the function always returns the same result when given the same428 arguments) and <span class="quote">“<span class="quote">strictness</span>”</span> (whether the function429 returns null if any argument is null). Consult the <a class="xref" href="sql-createfunction.html" title="CREATE FUNCTION"><span class="refentrytitle">CREATE FUNCTION</span></a>430 reference page for details.431 </p><p>432 When making use of these optimization attributes, your433 <code class="command">CREATE FUNCTION</code> statement might look something434 like this:435 436</p><pre class="programlisting">437CREATE FUNCTION foo(...) RETURNS integer AS $$438...439$$ LANGUAGE plpgsql STRICT IMMUTABLE;440</pre><p>441 </p></div></div><div class="sect2" id="PLPGSQL-PORTING-APPENDIX"><div class="titlepage"><div><div><h3 class="title">43.13.3. Appendix <a href="#PLPGSQL-PORTING-APPENDIX" class="id_link">#</a></h3></div></div></div><p>442 This section contains the code for a set of Oracle-compatible443 <code class="function">instr</code> functions that you can use to simplify444 your porting efforts.445 </p><a id="id-1.8.8.15.8.3" class="indexterm"></a><pre class="programlisting">446--447-- instr functions that mimic Oracle's counterpart448-- Syntax: instr(string1, string2 [, n [, m]])449-- where [] denotes optional parameters.450--451-- Search string1, beginning at the nth character, for the mth occurrence452-- of string2. If n is negative, search backwards, starting at the abs(n)'th453-- character from the end of string1.454-- If n is not passed, assume 1 (search starts at first character).455-- If m is not passed, assume 1 (find first occurrence).456-- Returns starting index of string2 in string1, or 0 if string2 is not found.457--458 459CREATE FUNCTION instr(varchar, varchar) RETURNS integer AS $$460BEGIN461 RETURN instr($1, $2, 1);462END;463$$ LANGUAGE plpgsql STRICT IMMUTABLE;464 465 466CREATE FUNCTION instr(string varchar, string_to_search_for varchar,467 beg_index integer)468RETURNS integer AS $$469DECLARE470 pos integer NOT NULL DEFAULT 0;471 temp_str varchar;472 beg integer;473 length integer;474 ss_length integer;475BEGIN476 IF beg_index > 0 THEN477 temp_str := substring(string FROM beg_index);478 pos := position(string_to_search_for IN temp_str);479 480 IF pos = 0 THEN481 RETURN 0;482 ELSE483 RETURN pos + beg_index - 1;484 END IF;485 ELSIF beg_index < 0 THEN486 ss_length := char_length(string_to_search_for);487 length := char_length(string);488 beg := length + 1 + beg_index;489 490 WHILE beg > 0 LOOP491 temp_str := substring(string FROM beg FOR ss_length);492 IF string_to_search_for = temp_str THEN493 RETURN beg;494 END IF;495 496 beg := beg - 1;497 END LOOP;498 499 RETURN 0;500 ELSE501 RETURN 0;502 END IF;503END;504$$ LANGUAGE plpgsql STRICT IMMUTABLE;505 506 507CREATE FUNCTION instr(string varchar, string_to_search_for varchar,508 beg_index integer, occur_index integer)509RETURNS integer AS $$510DECLARE511 pos integer NOT NULL DEFAULT 0;512 occur_number integer NOT NULL DEFAULT 0;513 temp_str varchar;514 beg integer;515 i integer;516 length integer;517 ss_length integer;518BEGIN519 IF occur_index <= 0 THEN520 RAISE 'argument ''%'' is out of range', occur_index521 USING ERRCODE = '22003';522 END IF;523 524 IF beg_index > 0 THEN525 beg := beg_index - 1;526 FOR i IN 1..occur_index LOOP527 temp_str := substring(string FROM beg + 1);528 pos := position(string_to_search_for IN temp_str);529 IF pos = 0 THEN530 RETURN 0;531 END IF;532 beg := beg + pos;533 END LOOP;534 535 RETURN beg;536 ELSIF beg_index < 0 THEN537 ss_length := char_length(string_to_search_for);538 length := char_length(string);539 beg := length + 1 + beg_index;540 541 WHILE beg > 0 LOOP542 temp_str := substring(string FROM beg FOR ss_length);543 IF string_to_search_for = temp_str THEN544 occur_number := occur_number + 1;545 IF occur_number = occur_index THEN546 RETURN beg;547 END IF;548 END IF;549 550 beg := beg - 1;551 END LOOP;552 553 RETURN 0;554 ELSE555 RETURN 0;556 END IF;557END;558$$ LANGUAGE plpgsql STRICT IMMUTABLE;559 560</pre></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="plpgsql-development-tips.html" title="43.12. 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