Instructions are too confusing, you need to state the columns you want returned. Also you shouldn't specify that the query should contain 'AS' since this isn't required.

If you are including prefixes in some of the names then you should probably have an optional column for those. It makes more sense than putting them in first_name or last_name.

Keep up the good work with the series. One small point, recieved should be received.

Looks good now. Cheers.

From looking at the solutions some people have passed without selecting all relevant columns that you specify in the description. You need more stringent test cases.

Also you should either add some example tests or delete the default stuff and add a note, as I tried to run the examples initially and got a failed message with 'users table does not exist' which could confuse people.

Fair point. I guess even with the wording it was still quite tricky to understand what I was looking for. This should make it more explicit. I've updated as per your suggestions (X & Y and X > Y). Thanks.

I used the Ruby library. If you go to create kata and change the language to SQL you should see an example of one way to do it and you can adjust as needed. Other than that I'd recommend joining the gitter channel for creating katas to get more in depth help (happy to chat there). This may also help - https://medium.com/@Codewars/new-sql-updates-its-even-easier-now-to-create-sql-kata-7ac8b329a968 Look forward to your kata!

In the examples you specify 'litres' but in the solution you ask for 'liters'. You should have conformity here. Probably also should specify which columns you want returned.