"An SQL Server database schema" or "a SQL Server database schema"? [duplicate]
Solution 1:
This depends, I would think, on your pronunciation of SQL. It can be pronounced as "sequel", or spelled out as "S-Q-L". That perhaps doesn't help in written English.
A thoroughly scientific survey of Google throws up many more hits for "an SQL" than "a SQL". This is also the form used on that Wikipedia article and elsewhere, such as this Microsoft SQL Server documentation entitled "Executing an SQL Query".