newid

Description

Generates human-readable, globally unique IDs (GUIDs) in two different formats, based on arguments you provide. The length of the human-readable format of the GUID value is either 32 bytes (with no dashes) or 36 bytes (with dashes).

Syntax

newid([optionflag])

Parameters

option flag

• 0, or no value – the GUID generated is human-readable (varchar), but does not include dashes. This argument, which is the default, is useful for converting values into varbinary.

• -1 – the GUID generated is human-readable (varchar) and includes dashes.

• -0x0 – returns the GUID as a varbinary.

• Any other value for newid returns NULL.

Examples

Example 1

Creates a table with varchar columns 32 bytes long, then uses newid with no arguments with the insert statement:

create table t (UUID varchar(32))
go
insert into t values (newid())
insert into t values (newid())
go
select * from t

UUID
--------------------------------
f81d4fae7dec11d0a76500a0c91e6bf6 
7cd5b7769df75cefe040800208254639

Example 2

Produces a GUID that includes dashes:

select newid(1)

------------------------------------
b59462af-a55b-469d-a79f-1d6c3c1e19e3

Example 3

Returns a new GUID of type varbinary for every row that is returned from the query:

select newid(0x0) from sysobjects

Example 4

Uses newid with the varbinary datatype:

sp_addtype binguid, "varbinary(16)"
create default binguid_dflt
as 
newid(0x0)
sp_bindefault "binguid_dflt","binguid"
create table T1 (empname char(60), empid int, emp_guid binguid)
insert T1 (empname, empid) values ("John Doe", 1)
insert T1 (empname, empid( values ("Jane Doe", 2)

Usage

• newid generates two values for the globally unique ID (GUID) based on arguments you pass to newid. The default argument generates GUIDs without dashes. By default newid returns new values for every filtered row.

• You can use newid in defaults, rules, and triggers, similar to other functions.

• Make sure the length of the varchar column is at least 32 bytes for the GUID format without dashes, and at least 36 bytes for the GUID format with dashes. The column length is truncated if it is not declared with these minimum required lengths. Truncation increases the probability of duplicate values.

• An argument of zero is equivalent to the default.

• Because GUIDs are globally unique, they can be transported across domains without generating duplicates.

Standards

ANSI SQL – Compliance level: Transact-SQL extension.

Permissions

Any user can execute newid.

Copyright © 2005. Sybase Inc. All rights reserved.

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