What is the string length of a GUID

Question

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

User · Accepted Answer

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 · Answer

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

User · Answer

The correct thing to do here is to store it as uniqueidentifier - this is then fully indexable  etc  at the database  The next-best option would be a binary 16  column  standard GUIDs are exactly 16 bytes in length   If you must store it as a string  the length really comes down to how you choose to encode it  As hex  AKA base-16 encoding  without hyphens it would be 32 characters  two hex digits per byte   so char 32    However  you might want to store the hyphens  If you are short on space  but your database doesn t support blobs   guids natively  you could use Base64 encoding and remove the    padding suffix  that gives you 22 characters  so char 22   There is no need to use Unicode  and no need for variable-length - so nvarchar max  would be a bad choice  for example

User · Answer

22 bytes  if you do it like this   System Guid guid   System Guid NewGuid    byte   guidbytes   guid ToByteArray    string uuid   Convert ToBase64String guidbytes  Trim

User · Answer

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 · Answer

GUIDs are 128bits  or   0 through ffffffffffffffffffffffffffffffff  hex  or  0 through 340282366920938463463374607431768211455  decimal  or  0 through 11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111  binary  base 2  or  0 through 91  lt b PX48m wVmVA 1y  base 95    So yes  min 20 characters long  which is actually wasting more than 4 25 bits  so you can be just as efficient using smaller bases than 95 as well  base 85 being the smallest possible one that still fits into 20 chars    0 through -r54lj NUUO Hi c2ym0  base 85  using 0-9A-Za-z      amp       - chars     -

User · Answer

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

[.net] What is the string length of a GUID?

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