This page in other versions: 9.2 / 9.3 / 9.4 / 9.5 / current (9.6)  |  Development versions: devel  |  Unsupported versions: 7.2 / 7.3 / 7.4 / 8.0 / 8.1 / 8.2 / 8.3 / 8.4 / 9.0 / 9.1

19.2. Structure of PL/pgSQL

PL/pgSQL is a block structured language. The complete text of a function definition must be a block. A block is defined as:

[ <<label>> ]
    declarations ]

Any statement in the statement section of a block can be a sub-block. Sub-blocks can be used for logical grouping or to localize variables to a small group of statements.

The variables declared in the declarations section preceding a block are initialized to their default values every time the block is entered, not only once per function call. For example:

   quantity INTEGER := 30;
   RAISE NOTICE ''Quantity here is %'',quantity;  -- Quantity here is 30
   quantity := 50;
   -- Create a sub-block
      quantity INTEGER := 80;
      RAISE NOTICE ''Quantity here is %'',quantity;  -- Quantity here is 80

   RAISE NOTICE ''Quantity here is %'',quantity;  -- Quantity here is 50

   RETURN quantity;
' LANGUAGE 'plpgsql';

It is important not to confuse the use of BEGIN/END for grouping statements in PL/pgSQL with the database commands for transaction control. PL/pgSQL's BEGIN/END are only for grouping; they do not start or end a transaction. Functions and trigger procedures are always executed within a transaction established by an outer query --- they cannot start or commit transactions, since PostgreSQL does not have nested transactions.

19.2.1. Lexical Details

Each statement and declaration within a block is terminated by a semicolon.

All keywords and identifiers can be written in mixed upper- and lower-case. Identifiers are implicitly converted to lower-case unless double-quoted.

There are two types of comments in PL/pgSQL. A double dash -- starts a comment that extends to the end of the line. A /* starts a block comment that extends to the next occurrence of */. Block comments cannot be nested, but double dash comments can be enclosed into a block comment and a double dash can hide the block comment delimiters /* and */.

Submit correction

If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.

Privacy Policy | About PostgreSQL
Copyright © 1996-2016 The PostgreSQL Global Development Group