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How to create a unique constraint on a varchar(max) field in visual studio, visually.
the problem is when i try it:
manage indexes and keys > add > columns
I can only chose the bigint columns, but not any of the varchar(max) ones.
Do I maybe have to use check constraints?
If yes, what to put in the expression?
Thnx for the info
You cannot put a unique constraint on a
VARCHAR(MAX)column (which could be up to 2 GB of text!!). You just simply cannot.The unique constraint is enforced by a unique index in the background, and SQL Server has a 900 byte limit on index entries. You also cannot put a unique constraint on a
VARCHAR(2000)field for that reason.You’ll need to find another way to achieve what you’re trying to do. You could e.g. calculate the length and something like a checksum over your text and put a unique constraint on those length and checksum columns.