postgresql raise exception
-- Simple exception:
RAISE EXCEPTION 'This user role does not exist.';
-- This example will abort the transaction with the given error message and
-- hint:
RAISE EXCEPTION 'Nonexistent ID --> %', user_id
USING HINT = 'Please check your user ID';
-- These two examples show equivalent ways of setting the SQLSTATE:
RAISE 'Duplicate user ID: %', user_id USING ERRCODE = 'unique_violation';
RAISE 'Duplicate user ID: %', user_id USING ERRCODE = '23505';
-- There is a second RAISE syntax in which the main argument is the condition
-- name or SQLSTATE to be reported, for example:
RAISE division_by_zero;
RAISE SQLSTATE '22012';
-- In this syntax, USING can be used to supply a custom error message, detail,
-- or hint. Another way to do the earlier example is
RAISE unique_violation USING MESSAGE = 'Duplicate user ID: ' || user_id;