If so which ones do you use?

SQL's or Structured Query language is a highly powerful and flexible way to select objects and edit data based on the object properties. They're particualrly useful for changing values and selecting nodes/links which have particular results.

If you have got some useful ones, please post them in this thread so that others can use? Hopefully we can start an online repository so that modellers can see how SQLs are used and see some examples. That way we can all build and analyse our models more efficiently.