Declaring Local Variables In PL/pgSQL Functions And Procedures

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You can declare local variables with :=, = in DECLARE clause as shown below:

CREATE FUNCTION my_func()
RETURNS INT
AS $$
DECLARE
  value1 INT := 1; -- Here
  value2 INT = 2; -- Here
  value3 INT DEFAULT 3; -- Here
  value4 CONSTANT INT := 4; -- Here
  value5 INT; -- Here
BEGIN
  RETURN value1 + value2 + value3;
END;
$$ LANGUAGE plpgsql;

    
    

    
    




*Memos:

:=, = and DEFAULT are the same.
Trying to change the constant local variable value4 gets error. 
The uninitialized local variable value5 is NULL. 
You can declare local variables with DECLARE clause in a PL/...