PL/pgSQL code is organized in blocks of code. This method of organization is known as
block structured code
Code blocks are entered within a SQL CREATE FUNCTION call that creates
the PL/pgSQL function in the PostgreSQL database. This CREATE FUNCTION command names the
new function, states its argument types, and states the return type. The function's main code block then starts with a
All variables are declared and optionally initialized to a default value in the declaration section of a code block.
A variable declaration specifies the variable's name and type. The declaration section is denoted by the
DECLARE keyword. Each variable declaration is ended with a semicolon.
After declaring variables, the main body of the code block is started with the BEGIN
keyword. The code block's statements should appear after the BEGIN keyword.
The END keyword designates the end of the code block. The main block of a PL/pgSQL
function should return a value of its specified return type and end any sub-blocks (code blocks started within another code
block) before its END keyword is reached.
Example 11-5 shows the structure of a PL/pgSQL code block.
Example 11-5. Structure of a PL/pgSQL code block
' LANGUAGE 'plpgsql';
A block of PL/pgSQL code can contain an unlimited amount of
, which are code blocks
nested within other code blocks. Sub-blocks are read and interpreted in the same manner as normal blocks; hence, they may
also contain sub-blocks of their own.
Sub-blocks can be useful for the organization of code within a large PL/pgSQL function. All sub-blocks must follow
normal block structure, meaning they must start with the DECLARE keyword, followed by the
BEGIN keyword and a body of statements, then end with the