SQL does not have FIRST
keyword it uses TOP
keyword. Full explanation here
http://technet.microsoft.com/en-us/library/ms189463.aspx
Firebird:
"In MS SQL 7 and above, the SELECT clause can take a TOP specifier to limit the number of rows returned. This feature is currently under development for the Firebird engine."
http://www.firebirdsql.org/manual/migration-mssql-syntax.html#migration-mssql-sql-cursors