PL/pgSQL
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| PL/pgSQL | |
|---|---|
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| Designed by | Jan Wieck |
| Developer | PostgreSQL Global Development Group |
| First appeared | October 30, 1998 |
| Template:Infobox software/simple | |
| Website | www |
| Influenced by | |
| PL/SQL, Ada | |
PL/pgSQL (Procedural Language/PostgreSQL) is a procedural programming language supported by the PostgreSQL ORDBMS. It closely resembles Oracle's PL/SQL language. Implemented by Jan Wieck, PL/pgSQL first appeared with PostgreSQL 6.4, released on October 30, 1998.[1] Version 9 also implements some ISO SQL/PSM features, like overloading of SQL-invoked functions and procedures.[2]
PL/pgSQL, as a fully featured programming language, allows much more procedural control than SQL, including the ability to use loops and other control structures. SQL statements and triggers can call functions created in the PL/pgSQL language.
The design of PL/pgSQL aimed to allow PostgreSQL users to perform more complex operations and computations than SQL, while providing ease of use. The language is able to be defined as trusted by the server.[3]
PL/pgSQL is one of the programming languages included in the standard PostgreSQL distribution,[4] the others being PL/Tcl, PL/Perl[5] and PL/Python.[6] In addition, many others are available from third parties, including PL/Java,[7] PL/pgPSM,[8] PL/php,[9] PL/R,[10] PL/Ruby,[11] PL/sh, PL/Lua, Postmodern[12] (based on Common Lisp) and PL/v8. PostgreSQL uses Bison as its parser,[13] making it easy to port many open-source languages, as well as to reuse code.
Comparing with PSM
The SQL/PSM language is specified by an ISO standard, but is also inspired by Oracle's PL/SQL and PL/pgPL/SQL, so there are few differences. The PL/pgPSM contributed module implements the standard. The main features of PSM that differ from PL/pgSQL:[8][14]
- Exception handlers are subroutines (continue handlers);
- Warnings can be handled as an exception;
- Declaration of variables should be based on SQL query results.
All three languages (Oracle PL/SQL,[15] PostgreSQL PL/pgSQL and ISO SQL/PSM[16]) were heavily influenced by the Ada programming language.
Example
The following example is a function that computes the sales tax of a given subtotal:
CREATE FUNCTION sales_tax(subtotal real) RETURNS real AS $$
BEGIN
RETURN subtotal * 0.06;
END;
$$ LANGUAGE plpgsql;
References
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- ^ Page Module:Citation/CS1/styles.css has no content."PostgreSQL Documentation, Appendix E: Release Notes, Release 6.4". PostgreSQL Global Development Group. January 2012.
- ^ Page Module:Citation/CS1/styles.css has no content."feature T322", SQL standard features (9 ed.), PostgreSQL.
- ^ Page Module:Citation/CS1/styles.css has no content."PL/pgSQL – SQL Procedural Language". PostgreSQL. Retrieved 2007-11-15.
- ^ Page Module:Citation/CS1/styles.css has no content."Procedural Languages". 9 May 2024.
- ^ Page Module:Citation/CS1/styles.css has no content."PL/Perl", Docs (current ed.), PostgreSQL.
- ^ Page Module:Citation/CS1/styles.css has no content."PL/Python", Docs (current ed.), PostgreSQL.
- ^ Page Module:Citation/CS1/styles.css has no content."PL/Java", Gborg (project), PostgreSQL.
- ^ a b Page Module:Citation/CS1/styles.css has no content.SQL/PSM (manual), PostgreSQL, 20 May 2008.
- ^ Page Module:Citation/CS1/styles.css has no content."PL/PHP", Community, Command prompt.
- ^ Page Module:Citation/CS1/styles.css has no content.Conway, Joe, PL/R, archived from the original on 2014-06-19, retrieved 2005-02-25.
- ^ Page Module:Citation/CS1/styles.css has no content.PL/Ruby (project), Ruby lang, 2018-11-23.
- ^ Page Module:Citation/CS1/styles.css has no content.Haverbeke, Marijn (2024-05-27), marijnh/Postmodern, retrieved 2024-06-01
- ^ Page Module:Citation/CS1/styles.css has no content."Parser stage", Docs (9 ed.), PostgreSQL
- ^ Page Module:Citation/CS1/styles.css has no content.Stehule, P, "Proposal: PL/pgPSM for pg9.3", Hackers (mailing list), PostgreSQL.
- ^ Page Module:Citation/CS1/styles.css has no content."C. PL/SQL Program Limits", PL/SQL Language Reference, Database Online Documentation (11g Release 1 (11.1) ed.), Oracle, p. 87,
PL/SQL is based on the programming language Ada.
- ^ Page Module:Citation/CS1/styles.css has no content."1", Stored procedures (ODP), O’Reilly.
