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basic 21
The challenge is based on this white paper (I think) so if you follow the examples step by step, you should be able to understand what's going on. https://crypto.stanford.edu/cs155/papers/sql_injection.pdf
MsSql used to be everywhere but it's probably not as commonly used nowadays as it once was.
Though the UK government and Microsoft cut some deal a while back, so most Local government sites, schools and councils, as well as things like the NHS are all still using the .Net framework.
No expense spared when you're dishng out taxpayers money.
We get at least 1 SQLi every 7-10 days, even from BIG UK/EU clients. Don't forget the http://codecurmudgeon.com/wp/sql-injection-hall-of-shame/