SQL>
SQL>
SQL>

Layout - is crucial for clarity

Build from the inner-most query first; use dummy values initially to help understanding

Quotes - The inner, or L1 query is enclosed by an opening and closing single quote

Double quotes - quotes are doubled where they already exist within an embedded query

Field Separator:

Use '|| chr(10) ||' to force a line feed

Use '||' as an alternative to the ',' field separator to eliminate any trailing spaces in a column attribute

The 'SET' enviroment controls:

Control your environment with the ‘set’ commands
Hold these settings in a script file to action before building spooled nested scripts
Switch selected items on/off within script files
Switch these settings back on via another script file at end