Hello, Suppose I have a huge table with 10 Columns. I create a unique constraint on the columns (col1, col2 col3) If I use theese columns in a query WHERE col1=x and col2=y and col3=z The Question is whether the optimizer use these constraint in queries? Because I find some information in sysindexes table. And what is the difference if I create an unique index on the same columns(col1, col2, col3) ? Is it a duplicate or is there any difference? Thanks.