Update Table values based on another table values

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 use the EXISTS clause.

For example:

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);

Whenever a supplier_id matched a customer_id value, the supplier_name would be overwritten to the customer name from the customers table.