duplicate null value violation on UNIQUE KEY constraint in Mssql
you can create a unique index that ignores null values like this
CREATE UNIQUE NONCLUSTERED INDEX idx_col1ON dbo.MyTable(col1)WHERE col1 IS NOT NULL;
you can create a unique index that ignores null values like this
CREATE UNIQUE NONCLUSTERED INDEX idx_col1ON dbo.MyTable(col1)WHERE col1 IS NOT NULL;