aggiungi un indice che non ammette duplicati

CREATE UNIQUE NONCLUSTERED INDEX [IX_tabella] ON [dbo].[tabella]
(
[fk1] ASC,
[fk2] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO