Question

The only answer I’ve come close to accepting is one involving the setting of a UNIQUE constraint on a column.

What I need to do is:

…in sql, to disallow duplicate entries between TWO columns. So, say I have two columns, ‘Parcel’ and ‘Year’. How would I go about disallowing a duplicate entry of Parcel = 1, Year = 1, and Parcel = 1, Year = 1? I need to do this while still allowing duplicates in each respective column, just disallowing

Answer 1

Add a UNIQUE constraint the spans those two columns:

ALTER TABLE table_name
add CONSTRAINT constraint_name UNIQUE (Parcel, Year);