Query error with ambiguous column name in SQL

Question

I get an Ambiguous column name error with this query (InvoiceID). I can\'t figure out why. They all seem to be joined correctly so why doesn\'t the management studio know to

Answer 1

This happens because there are fields with the same name in more than one table, in the query, because of the joins, so you should reference the fields differently, giving names (aliases) to the tables.