Question

I used to prevent empty strings for a field in InterBase by set a file to not null but in firebird it is different of the user type any thing in the file and then save and then delete that string the fiel will be store empty string no null and setting the field to no null will not prevent that action

Is there a way to prevent the user to enter empty string from the database side ?

thanks

Answer 1

You can use trigger like this

CREATE OR ALTER TRIGGER YOUR_TABELE_BIU0 FOR YOUR_TABELE
ACTIVE BEFORE INSERT OR UPDATE POSITION 0
AS
begin
  IF (CHAR_LENGTH(new.YOURFIELD)=0) THEN
    exception E_NOT_EMPTY 'field can not be empty';
end