PL/pgSQL

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PL/pgSQL (Procedural Language/PostgreSQL) is a procedural programming language supported by the PostgreSQL ORDBMS. It closely resembles Oracle's PL/SQL language. Released with v7 in 2000,[1] with PostgreSQL v9 some ISO SQL/PSM features, like overloading of SQL-invoked functions and procedures,[2] are supported.

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. Functions created in the PL/pgSQL language can be called from an SQL statement, or as the action that a trigger performs.

PL/pgSQL was created to be able to perform more complex operations and computations than SQL, while being easy to use, and is able to be defined as trusted by the server.[3]

PL/pgSQL is the only programming language installed by default for PostgreSQL, but many others are available, including PL/Java,[4] PL/Perl,[5] PL/pgPSM,[6] PL/php,[7] PL/Python,[8] PL/R,[9] PL/Ruby,[10] PL/sh, PL/Tcl, and PL/Lua. PostgreSQL uses Bison as its parser,[11] so it is easy to port many open source languages, as well as reuse code.

Comparing with PSM[edit]

The SQL/PSM language is specified by an ISO standard, but is also inspired by Oracle's PL/SQL and 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:[6][12]

  • Exception handlers are subroutines (continue handlers);
  • Warnings can be handled like an exception;
  • Declaration of variables should be based on SQL query result.

All three languages (Oracle PL/SQL,[13] PostgreSQL PL/pgSQL and ISO SQL/PSM[14]) are originally descended from the Ada programming language.

References[edit]

  1. ^ Cunningham, Lewis (2011), "1. Introduction to EnterpriseDB: A Mini-History of PostgreSQL", EnterpriseDB, The Definitive Reference: The Oracle-Compatible Enterprise database, Databases IT In-Focus Series (5), ISBN 0-9776715-7-7, PostgreSQL 7.0 was released mid-year in 2000. […] it had an embedded language, PL/pgSQL. It actually supported several Languages… 
  2. ^ "feature T322", SQL standard features (9 ed.), PostgreSQL .
  3. ^ "PL/pgSQL – SQL Procedural Language". PostgreSQL. Retrieved 2007-11-15. 
  4. ^ "PL/Java", Gborg (project), PostgreSQL .
  5. ^ "PL/Perl", Docs (current ed.), PostgreSQL .
  6. ^ a b SQL/PSM (manual), PostgreSQL .
  7. ^ "PL/PHP", Community, Command prompt .
  8. ^ "PL/Python", Docs (current ed.), PostgreSQL .
  9. ^ Conway, Joe, PL/R .
  10. ^ PL/Ruby (project), Ruby lang .
  11. ^ "Parser stage", Docs (9 ed.), PostgreSQL .
  12. ^ Stehule, P, "Proposal: PL/pgPSM for pg9.3", Hackers (mailing list), PostgreSQL .
  13. ^ "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. 
  14. ^ "1", Stored procedures (ODP), O’Reilly .

External links[edit]