MySQL Trigger - Storing a SELECT in a variable

Question

I have a trigger in which I want to have a variable that holds an INT I get from a SELECT, so I can use it in two IF statements instead of calling the SEL

Answer 1

`CREATE TRIGGER `category_before_ins_tr` BEFORE INSERT ON `category`
  FOR EACH ROW
BEGIN
    **SET @tableId= (SELECT id FROM dummy LIMIT 1);**

END;`;