Uniqueidentifier data type in SQL Server

the uniqueidentifier data type can store 16-byte binary values, which act the same as the Globally Unique Identifier (guid. GUID is the unique binary number: No duplicate guid value is generated on any two computers in the world.

in SQL, rowguidcol indicates that the new column is the Globally Unique Identifier column of the row. Only one uniqueidentifier column can be assigned to each table as the rowguidco column. The rowguidcol attribute can only be assigned to the uniqueidentifier column

uniqueidentifier:

1. use the newid () function to implement

2. directly convert the constant of the string to XXXXXXXX-XXXX-xxxxxxxxxxxx

example: 6f9619ff-8b86-d011-b42d-00c04fc964ff

3. directly assign 32-bit sixteen-Bit Data

example: 0xffffffffff00000000ffffffff00000000