INFORMATICA Source qualifier SQL query

Question

I'm new to informatica. I was going through few mapping in which one had 4 source table (oracle)connected to single source qualifier and they used SQL queries in SQ.

In SQ- SQL query part: They used 6 tables with some joins to pick few columns(from all 6 tbls) where couple of fields doesn't exist in source definition itself.
Questions: In that case, is it necessary to connect the port from source definition to SQ?

Can we use union function inside SQL query?

Thank you in advance!!!

Answer 1

No it's not necessary to connect the ports. But as a convention you should.

Yes you can use union inside Source Qualifier query to join multiple tables. Also you can join tables for which source definition is not present in the mapping but is in same database.