Never leave it a mystery - Multiple sources for one SQ

When you have different table joins in the source-qualifier, it is a bad practice to include the table in the SQL and not make it visible in the mapping, Though PowerCenter works fine without the source defined in Source Analyzer, it is a good practice to define the source then drag it to the mapping onto the common source qualifier.

Don't make your SQL override of the Source Qualifier orphan. The actual tables used in the query FROM clause have to be part of the mapping and should be visible in the mapping attached to the same source qualifier.