A globally unique identifier (GUID).
A column or local variable of uniqueidentifier data type can be initialized to a value in two ways:
Comparison operators can be used with uniqueidentifier values. However, ordering is not implemented by comparing the bit patterns of the two values. When using uniqueidentifier data, the only operations allowed are the equality comparison operators (= and <>) and the IS NULL and IS NOT NULL operators. No other inequality comparison or arithmetic operators are allowed. All column constraints and properties except IDENTITY are allowed on the uniqueidentifier data type.
| ALTER TABLE | DELETE |
| CAST and CONVERT | INSERT |
| CREATE TABLE | NEWID |
| Data Type Conversion | Overview of Replication |
| Data Types | SET @local_variable |
| DECLARE @local_variable | UPDATE |