CREATE OR REPLACE PROCEDURE PRC_TWO_DAY_EXTEND AS BEGIN UPDATE CHECKOUT SET CHECK_IN_DATE = CHECK_IN_DATE + 2 JOIN PATRON ON PATRON.PAT_ID = CHECKOUT.PAT_ID FROM CHECKOUT WHERE PATRON.PAT_TYPE = 'STUDENT'; END; EXEC PRC_TWO_DAY_EXTEND; Basically I need to just add two days to the check in date but I cant figure out how to join them and then update them, because its based on whether or not PAT_TYPE = 'STUDENT'
Your date arithmetics suggests Oracle, so let me assume that's the database you are running.
In that database, you could phrase the query as:
update checkout c set check_in_date = check_in_date + 2 where exists ( select 1 from patron p where p.pat_id = c.pat_id and p.pat_type = 'STUDENT' ) This updates the check-in date of rows whose pat_id can be found in patron with a pat_type having value 'STUDENT'.
Yet another option is to use the MERGE as follows:
Merge into checkout c Using (select pat_id From patron Where pat_type = 'STUDENT') p On (p.pat_id = c.pat_id) When matched then Update set c.check_in_date = c.check_in_date + 2 