NEWSEQUENTIALID() can only be used with DEFAULT constraints on table columns of type uniqueidentifier. For example:
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CREATE TABLE myTable (ColumnA uniqueidentifier DEFAULT NEWSEQUENTIALID()) |
When NEWSEQUENTIALID() is used in DEFAULT expressions, it cannot be combined with other scalar operators. For example, you cannot execute the following:
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CREATE TABLE myTable (ColumnA uniqueidentifier DEFAULT dbo.myfunction(NEWSEQUENTIALID())) |
In the previous example, myfunction() is a scalar user-defined scalar function that accepts and returns a uniqueidentifier value.
NEWSEQUENTIALID() cannot be referenced in queries.
You can use NEWSEQUENTIALID() to generate GUIDs to reduce page contention at the leaf level of indexes.
Each GUID generated by using NEWSEQUENTIALID() is unique on that computer. GUIDs generated by using NEWSEQUENTIALID() are unique across multiple computers only if the source computer has a network card. For more information about GUIDs, see Using uniqueidentifier Data.