Cool SQL functions

[dethfire]

Where can I find a site that explains all the SQL functions. I already know all the basic Selects, Joins... I'm looking for real useful stuff. For instance addition, concatonation, tops, sums...

[Hierophant]

SQL doesn't have functions. Each Database system implements their own functions for use within queries.

[MattR]

I think the basic math functions are standard SQL, e.g.
+, -, *, /

SUM, COUNT, MAX, MIN, AVG

Google is your friend, this is what I found immediately on searching for 'SQL Functions'
http://www.oreilly.com/catalog/sqlnut/chapter/ch04.html