how to declare variable in PostgreSQL

Question

I try to declare a variable in a code like this, but it\'s doesn\'t work. Can you tell me what\'s the problem?

ERROR:  syntax error at or near \"VARCHAR\"
LI         


        

Answer 1

Create a new setting in postgresql.conf for custom_variable_classes:

custom_variable_classes = 'var'

Reload the config, you now have the variable "var" available in all your databases.

To create the variable p_country, just use SET:

SET var.p_country = 'US';
SELECT current_setting('var.p_country') AS p_country;

It's not a beauty, but it works.

Answer 2

Within a PL/pgSQL function you can declare variables like this:

CREATE FUNCTION identifier (arguments) RETURNS type AS '
  DECLARE

     -- Declare an integer.
    subject_id INTEGER;

     -- Declare a variable length character.
    book_title VARCHAR(10);

      -- Declare a floating point number.
    book_price FLOAT;

  BEGIN
    statements
  END;
' LANGUAGE 'plpgsql';

Source: http://www.commandprompt.com/ppbook/x19832