Raising error in postgreSQL

Question

CREATE OR REPLACE FUNCTION msgfailerror() RETURNS trigger AS 
\' BEGIN 
    IF NEW.noces< new.first_column THEN 
        RAISE EXCEPTION \'cannot have a negative sala         


        

Answer 1

I agree with Frank that you could better use constraints, but you call it validation. Validation is typically done before insertion takes place. If you would like to validate insertions, you could use functions instead of triggers or constraints.

When you would write functions is the answer to your question to raise exceptions or notices that as long as there has been no write action a notice would suffice (together with leaving the function). Once there has been a write to the database, do you have to use exceptions as they perform a rollback.

Like this:

CREATE OR REPLACE FUNCTION field_validate(p_int int) RETURNS boolean AS $$

DECLARE
 i_id int;
BEGIN 
  if p_int > 10 then
   raise notice 'should be smaller then 10';
   return false;
  end if;
  insert into tbl_numbers(firstfield) values(p_int) returning id in i_id;
  insert into tbl_fake(nofield) values(i_id);
  return true;
EXCEPTION
  WHEN raise exception THEN
   return false;
END;
$$ LANGUAGE plpgsql;