MySQL – specific columns on join?

When making a join (inner, left outer, right outer or whatever), how can I specify which columns on the table to join into the original table?

Consider the following example:

SELECT FirstName FROM User LEFT OUTER JOIN Provider ON User.ProviderID = Provider.ID

This would select FirstName from user, but select everything from Provider. How can I specify which parts of Provider should be included in the resultset?

Answer

This will only include User.FirstName and Provider.ProviderID in the final resultset:

SELECT User.FirstName, Provider.ProviderID FROM User LEFT OUTER JOIN Provider ON User.ProviderID = Provider.ID