What is the string length of a GUID?

Shimmy_75500 0
Viewed 409645

I want to create a varchar column in SQL that should contain N'guid' while guid is a generated GUID by .NET (Guid.NewGuid) - class System.Guid.

What is the length of the varchar I should expect from a GUID? Is it a static length?

Should I use nvarchar (will GUID ever use Unicode characters)?

varchar(Guid.Length)

PS. I don't want to use a SQL row guid data-type. I am just asking what is Guid.MaxLength.

sql-types string-length varchar guid .net
7 Answers

It depends on how you format the Guid:

  • Guid.NewGuid().ToString() = 36 characters (Hyphenated)
    outputs: 12345678-1234-1234-1234-123456789abc

  • Guid.NewGuid().ToString("D") = 36 characters (Hyphenated, same as ToString())
    outputs: 12345678-1234-1234-1234-123456789abc

  • Guid.NewGuid().ToString("N") = 32 characters (Digits only)
    outputs: 12345678123412341234123456789abc

  • Guid.NewGuid().ToString("B") = 38 characters (Braces)
    outputs: {12345678-1234-1234-1234-123456789abc}

  • Guid.NewGuid().ToString("P") = 38 characters (Parentheses)
    outputs: (12345678-1234-1234-1234-123456789abc)

  • Guid.NewGuid().ToString("X") = 68 characters (Hexadecimal)
    outputs: {0x12345678,0x1234,0x1234,{0x12,0x34,0x12,0x34,0x56,0x78,0x9a,0xbc}}

user_890750

36, and the GUID will only use 0-9A-F (hexidecimal!).

12345678-1234-1234-1234-123456789012

That's 36 characters in any GUID--they are of constant length. You can read a bit more about the intricacies of GUIDs here.

You will need two more in length if you want to store the braces.

Note: 36 is the string length with the dashes in between. They are actually 16-byte numbers.

user_955890

I believe GUIDs are constrained to 16-byte lengths (or 32 bytes for an ASCII hex equivalent).

user_1118660

Binary strings store raw-byte data, whilst character strings store text. Use binary data when storing hexi-decimal values such as SID, GUID and so on. The uniqueidentifier data type contains a globally unique identifier, or GUID. This value is derived by using the NEWID() function to return a value that is unique to all objects. It's stored as a binary value but it is displayed as a character string.

Here is an example.

USE AdventureWorks2008R2;
GO
CREATE TABLE MyCcustomerTable
(
    user_login   varbinary(85) DEFAULT SUSER_SID()
    ,data_value   varbinary(1)
);
GO

INSERT MyCustomerTable (data_value)
    VALUES (0x4F);
GO

Applies to: SQL Server The following example creates the cust table with a uniqueidentifier data type, and uses NEWID to fill the table with a default value. In assigning the default value of NEWID(), each new and existing row has a unique value for the CustomerID column.

-- Creating a table using NEWID for uniqueidentifier data type.  
CREATE TABLE cust  
(  
 CustomerID uniqueidentifier NOT NULL  
   DEFAULT newid(),  
 Company varchar(30) NOT NULL,  
 ContactName varchar(60) NOT NULL,   
 Address varchar(30) NOT NULL,   
 City varchar(30) NOT NULL,  
 StateProvince varchar(10) NULL,  
 PostalCode varchar(10) NOT NULL,   
 CountryRegion varchar(20) NOT NULL,   
 Telephone varchar(15) NOT NULL,  
 Fax varchar(15) NULL  
);  
GO  
-- Inserting 5 rows into cust table.  
INSERT cust  
(CustomerID, Company, ContactName, Address, City, StateProvince,   
 PostalCode, CountryRegion, Telephone, Fax)  
VALUES  
 (NEWID(), 'Wartian Herkku', 'Pirkko Koskitalo', 'Torikatu 38', 'Oulu', NULL,  
 '90110', 'Finland', '981-443655', '981-443655')  
,(NEWID(), 'Wellington Importadora', 'Paula Parente', 'Rua do Mercado, 12', 'Resende', 'SP',  
 '08737-363', 'Brasil', '(14) 555-8122', '')  
,(NEWID(), 'Cactus Comidas para Ilevar', 'Patricio Simpson', 'Cerrito 333', 'Buenos Aires', NULL,   
 '1010', 'Argentina', '(1) 135-5555', '(1) 135-4892')  
,(NEWID(), 'Ernst Handel', 'Roland Mendel', 'Kirchgasse 6', 'Graz', NULL,  
 '8010', 'Austria', '7675-3425', '7675-3426')  
,(NEWID(), 'Maison Dewey', 'Catherine Dewey', 'Rue Joseph-Bens 532', 'Bruxelles', NULL,  
 'B-1180', 'Belgium', '(02) 201 24 67', '(02) 201 24 68');  
GO
user_87369770
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