PostgreSQL, Second Edition

Language Structure

PL/pgSQL is termed a block-structured language. A block is a sequence of statements between a matched set of DECLARE/BEGIN and END statements. Blocks can be nested—meaning that one block can entirely contain another block, which in turn can contain other blocks, and so on. For example, here is a PL/pgSQL function:

 1 -- 2 -- ch07.sql 3 -- 4 5 CREATE OR REPLACE FUNCTION my_factorial(value INTEGER) RETURNS INTEGER AS $$ 6 DECLARE 7 arg INTEGER; 8 BEGIN 9 10 arg := value; 11 12 IF arg IS NULL OR arg < 0 THEN 13 RAISE NOTICE 'Invalid Number'; 14 RETURN NULL; 15 ELSE 16 IF arg = 1 THEN 17 RETURN 1; 18 ELSE 19 DECLARE 20 next_value INTEGER; 21 BEGIN 22 next_value := my_factorial(arg - 1) * arg; 23 RETURN next_value; 24 END; 25 END ...