Create an index in SQL Server.
CREATE INDEX [IX_TABLENAME_FIELDNAME] ON [dbo].[TABLENAME] ([FIELDNAME])
CREATE INDEX [IX_TABLENAME_FIELDNAME1_FIELDNAME2] ON [dbo].[TABLENAME] ([FIELDNAME1], [FIELDNAME2])
CREATE INDEX [IX_TABLENAME_FIELDNAME] ON [dbo].[TABLENAME] ([FIELDNAME]) INCLUDE ([FIELDNAME1], [FIELDNAME2])