HOW do i do a data append against multiple columns - mysql

Question

I added a column into table A and right now it is empty. What i want to do is take the phone column from table consumer and input it into appphone of table diabetic as long as the first name, last name, address, city, state, and zip, match up in both tables. Below is the query i have been trying and in theory should work but is not. I keep getting the same error no matter which way i change the query.--
error 'subquery returns more than one row'
UPDATE Diabetic_DB
SET Diabetic_DB.AppPhone = (SELECT Consumer.PHONE FROM Consumer
WHERE Consumer.FN = Diabetic_DB.FirstName
and Consumer.LN = Diabetic_DB.LastName and Consumer.ADDR = Diabetic_DB.Address1
and Consumer.CITY = Diabetic_DB.City and Consumer.ST = Diabetic_DB.State
and Consumer.ZIP = Diabetic_DB.Zip)
WHERE EXISTS (SELECT DISTINCT(PHONE) FROM Consumer WHERE Consumer.FN = Diabetic_DB.FirstName
and Consumer.LN = Diabetic_DB.LastName and Consumer.ADDR = Diabetic_DB.Address1
and Consumer.CITY = Diabetic_DB.City and Consumer.ST = Diabetic_DB.State
and Consumer.ZIP = Diabetic_DB.Zip)
the original query i ran looked like this.
UPDATE Diabetic_DB
SET Diabetic_DB.AppPhone = Consumer.PHONE
WHERE EXISTS (SELECT * FROM Consumer WHERE Consumer.FN = Diabetic_DB.FirstName
and Consumer.LN = Diabetic_DB.LastName and Consumer.ADDR = Diabetic_DB.Address1
and Consumer.CITY = Diabetic_DB.City and Consumer.ST = Diabetic_DB.State
and Consumer.ZIP = Diabetic_DB.Zip)

Answer 1

Try something like this:
UPDATE Diabetic_DB
INNER JOIN Consumer ON
Consumer.FN = Diabetic_DB.FirstName
and Consumer.LN = Diabetic_DB.LastName and Consumer.ADDR = Diabetic_DB.Address1
and Consumer.CITY = Diabetic_DB.City and Consumer.ST = Diabetic_DB.State
and Consumer.ZIP = Diabetic_DB.Zip
SET Diabetic_DB.AppPhone = Consumer.PHONE