A programmer who works with Microsoft SQL Server.
SQL Server Minesweeper, anyone?

Interesting posts:
SQL Server: How to rotate a table 45 degrees?
SQL Server: A Puzzle solved in SQL
SQL Server: Recursive CTE, why Row_Number doesn't work
SQL Server: Clustered index key update = delete + update!

Other interesting posts:
SQL: SUMPRODUCT operator in MSSQL, MySQL, Oracle?
SQL Server: SQRT() vs POW() bake off
SQL Server: String or binary data would be truncated
SQL: Check if string is numeric (MSSQL, MySQL, Oracle)
SQL Server: Better ISDATE function for format 103 (dmy)
SQL Server: Symmetric matrix manipulation
Oracle: Using MODEL to perform iterative calculations

Essential Online Tools:
SQL Fiddle
Format tab values as Text-Table