#update statement

Updating records in one table based on values in another table:

You may wish to update records in one table based on values in another table. Since you can't list more than one table in the UPDATE statement, you can do a join. You dont want to use EXISTS clause as shown at the end which is wrong way of doing it.

This is the way to do it

UPDATE suppliers SET supplier_name = t2.name FROM suppliers t1 JOIN customers t2 on t1.supplier_id = t2.customer_id

I saw in here http://www.techonthenet.com/sql/update.php they use EXISTS clause which shouldn't be practiced

DONT do this:

UPDATE suppliers SET supplier_name =( SELECT customers.name FROM customers WHERE customers.customer_id = suppliers.supplier_id) WHERE EXISTS   ( SELECT customers.name     FROM customers     WHERE customers.customer_id = suppliers.supplier_id)