introduce

• GUID is a 16-byte GUID.
• A column or local variable of uniqueidentifier data type can be initialized to a value in the following ways:

▸ By using the [NEWID] or [NEWSEQUENTIALID] functions.
▸ By converting from a string constant in the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, in which each x is a hexadecimal digit in the range 0-9 or a-f. For example, 6F9619FF-8B86-D011-B42D-00C04FC964FF is a valid uniqueidentifier value.