How do I put an 'if clause' in an SQL string?

Question

So here\'s what I want to do on my MySQL database.

I would like to do:

SELECT *
    FROM itemsOrdered
    WHERE purchaseOrder_ID = \'@purchaseOr         


        

Answer 1

You can use the multiple-table UPDATE syntax to effect an ANTI-JOIN between purchaseOrder and itemsOrdered:

UPDATE purchaseOrder p LEFT JOIN itemsOrdered i
    ON p.purchaseOrder_ID = i.purchaseOrder_ID
   AND i.status = 'PENDING'
SET    p.purchaseOrder_status = 'COMPLETED'
WHERE  p.purchaseOrder_ID = '@purchaseOrder_ID'
   AND i.purchaseOrder_ID IS NULL