MySQL: Update all rows in a table matching results of another query

Question

I\'ve written a query returning rows associating Customers and Salespeoeple.

Note that the query joins several database tables. And note that not all c

Answer 1

Using subqueries

Most widely supported option

UPDATE INVOICES
   SET s_id = (SELECT cs.s_id
                 FROM CUSTOMERS_AND_SALES cs
                WHERE cs.c_id = INVOICES.c_id),
       s_name = (SELECT cs.s_name
                   FROM CUSTOMERS_AND_SALES cs
                  WHERE cs.c_id = INVOICES.c_id)
 WHERE INVOICES.c_id IN (SELECT cs.s_id
                           FROM CUSTOMERS_AND_SALES cs)

Using JOINs

UPDATE INVOICES
  JOIN CUSTOMERS_AND_SALES cs ON cs.c_id = INVOICES.c_id
   SET s_id = cs.s_id,
       s_name = cs.s_name

Answer 2

Assuming your first table is named customers and those customers without a salesperson have an s_id of NULL

UPDATE invoices JOIN customers USING (c_id)
SET invoices.s_id = customers.s_id, invoices.s_name = customers.s_name
WHERE customers.s_id IS NOT NULL;

I suggest testing in development or running a SELECT query using the JOIN above first to ensure the results.

Answer 3

You can create a view to make your UPDATE statement simple. The view should contain your query (in your case the query that associates customers and salespeople). Then update your table (invoices in your case) like this:

update TableToUpdate ttu, MyView mv
set ttu.column = mv.column
where ttu.key = mv.key