Crowd Q&A sites – particularly StackOverflow – are a massive help if you are struggling with a tech problem, but one of the niggles is that it is sometimes hard to communicate your issue. Posting example code and error logs helps, but it is not the same as being able to let someone else quickly run the code to see what happens. The same goes for people trying to help out by posting answers.
Well, for SQL issues there is now a tool you can use to share examples that people can experiment with online: SQLFiddle. You can select a database, build a schema, populate it with data and run queries against it. All the main RDBMSs are supported.