SQL – Index
UNIQUE Creates a unique index on a table or view. A unique index is one in which no two rows are permitted to have the same index key value. A clustered index on a view must be unique. The Database Engine does not allow creating a unique index on columns that already include duplicate values, whether or not IGNORE_DUP_KEY is set to ON. If this is tried, the Database Engine displays an error message. Duplicate values must be removed before
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