Question

I have 2 tables:

TBL1

• STDNum
• ID
• Check

TBL2

• STDNum
• UpdateMe

the STDNum is the common column. In TBL1, the same STDNum can have multiple rows with different IDs (It’s not the case on TBL2). The result I wanted is to Update the UpdateMe Column in TBL2 (setting its value to 1) IF (and only IF) the Check column in TBL1 for that Particular STDNum is all set to 1.

Can anybody please help me? or any idea please?

Answer 1

UPDATE  tbl2 b
        INNER JOIN
        (
            SELECT  STDNum
            FROM    tbl1 s
            GROUP   BY STDNum
            HAVING  MAX(s.check) = MIN(s.Check) AND
                    MAX(s.Check) = 1
        ) a ON a.STDNum = b.STDNum
SET     b.UpdateMe = 1

OR

UPDATE  tbl2 b
        INNER JOIN
        (
            SELECT  STDNum
            FROM    tbl1
            GROUP   BY STDNum
            HAVING  SUM(Check = 1) = COUNT(*)
        ) a ON a.STDNum = b.STDNum
SET     b.UpdateMe = 1