Primary Key vs Uniqueindentifier vs Unique Key in SQL Server

---

- Primary key -- Only one Identity column -- Can't be null

- Identity -- Automatic value -- Only one Identity column -- Can't be null -- Can exist in addition of primary key, GUID-auto columns

- Uniqueindentifier -- Can be multiple -- Can be null

- Uniqueindentifier - rowguid -- Auto generated -- Only one Identity column -- Can be null -- Can exist in addition of primary key, Identity columns

- Unique Key

-- Can be null
-- Can be multiple

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