Question

I have two table in my SQL Database
One is Companies & Another is Company_advertisements.
I want to update field of company table “adv”

SET Company.adv = 1 if Company_adv.image is not empty
SET Company.adv = 0 if Company_adv.image is empty

The foreign key for Company_adv table is company_id

I tried using the following syntax but it didn’t worked.Instead after running this query all the values of Companmy.adv become 1 after that

I tried this query:

UPDATE companies cmp, company_adv cma 
SET    cmp.adv=1 
WHERE  cma.company_id=cmp.id AND 
       cma.image1 IS NOT NULL

Please help me !!

Answer 1

if that’s the case, you need to use LEFT JOIN

UPDATE  companies cmp
        LEFT JOIN company_adv cma
            ON cmp.id = cma.company_id
SET     cmp.adv = IF(cma.image1 IS NULL, 0, 1)