Question

I have a table (custTAB) which has some zip codes missing, but has city, state names. I have a zipTAB which has a city, state and zip codes. My intent is to copy the missing zip codes from zipTAB to custTAB. However, for some reason my update doesn’t work as intended. If there were 10K NULL cust_zips, after the update I get 20K NULL cust_zips. Can someone check what’s going on? )

update custTAB 
   set cust_zip = (select zip 
                     from zipTAB 
                    where custTAB.cust_zip  is null and 
                          custTAB.cust_city   =  zipTAB.city and 
                          custTAB.cust_state  =  zipTAB.state 
                    limit 1 
                  );

Thanks.
PS: The row numbers are edited for easier reading.

Answer 1

can you try this one? you need to join the two tables:

UPDATE custTab a INNER JOIN zipTab b ON
        a.cust_city = b.city AND
        a.cust_state = b.state
SET a.cust_zip = b.zip
WHERE a.cust_zip IS NULL