NEWID - Transact-SQL System Functions - SQL Server

NEWID (Transact-SQL)

Returns a uniqueidentifier value that is guaranteed to be unique across all computers and all times. A uniqueidentifier is a 16-byte GUID.

Syntax

NEWID ( )

Return Value

Returns a uniqueidentifier value.

Description

The NEWID function generates a new globally unique identifier (GUID) for each row returned in a query result set. If you need to generate a GUID within your application code, use the Guid.NewGuid() method in the .NET Framework.

The GUID generated by NEWID is a version 4 UUID, which means it's a randomly generated GUID.

Examples

A. Creating a table with a default uniqueidentifier column

The following example creates a table with a uniqueidentifier column named ID. The NEWID() function is used as the default value for the ID column. This means that when a new row is inserted without specifying a value for ID, a new GUID is automatically generated.


CREATE TABLE MyTable (
    ID uniqueidentifier PRIMARY KEY DEFAULT NEWID(),
    ProductName varchar(100) NOT NULL,
    Price money
);



INSERT INTO MyTable (ProductName, Price) VALUES ('Laptop', 1200.00);
INSERT INTO MyTable (ProductName, Price) VALUES ('Keyboard', 75.00);



SELECT * FROM MyTable;

Output:

ID	ProductName	Price
A1B2C3D4-E5F6-7890-1234-567890ABCDEF	Laptop	1200.00
F9E8D7C6-B5A4-3210-FEDC-BA9876543210	Keyboard	75.00

B. Generating a GUID within a query

The following example simply returns a new GUID without inserting it into a table.


SELECT NEWID() AS NewGUID;

Output (the GUID will vary):

NewGUID
00000000-1111-2222-3333-444444444444

Remarks

NEWID() is an indeterministic function. Each time NEWID() is called in a query, it returns a different GUID.
The NEWID() function can be used in SELECT, WHERE, and ORDER BY clauses, as well as in DEFAULT constraints.
For generating GUIDs in application code, consider using the Guid.NewGuid() method in the .NET Framework.

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