Question

I'm new to SQL, are there references to get me started?

Answer 1

As noted in the SQL Gotchas section of Using the NOAO Data Lab, here are some good tutorials on SQL, and two links specific to PostgreSQL, the database technology used by the Data Lab:

Khan Academy Intro to SQL: Querying and managing data 

Online SQL Tutorial; learn the mechanics interactively

Try some other online exercises geared to PostgreSQL 

PostgreSQL SQL Language from the online manual

For specifics on the Astronomical Data Query Language (ADQL) used by the Data Lab TAP service, the IVOA maintains a reference manual.

Answer 2

Learn about SQL in an astronomical context with SkyServer at the SDSS Date Release 13 (DR13) search page:

http://skyserver.sdss.org/dr13/en/tools/search/sql.aspx

Plenty of astronomy examples and explanation.