you favorite editor, so far you are a programmer.
SQL Builderis a part of DB2. Read tutorials/doc, it is described there.
Also exist third-party software, but it cost.

I can't add somthing to what kdima said. As for me, I'm happy with vim. Each sql statement I put in a file, and after years I got a huge library. It is not useful only, it is memory also :)
I do not mean select * from table
I've been tought to type each query in a file, it gives additional time to think befor run.