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How long is a guid

Posted on 2006-03-23
Medium Priority
Last Modified: 2011-10-03
I am generating a GUID and need to store this value in a db table. How long does the varchar datatype need to be to hold this value ?
Question by:nmretd
LVL 35

Expert Comment

ID: 16271735
Depends on the GUID, but is usually a 128 bit number.  Therefore you need at least 128 and then some GUIDs have dashes or spaces to break it up into more readable sections - hence that is shy I said it depends.  I would say that 150 should be plenty for all cases.

Accepted Solution

SmithJW earned 100 total points
ID: 16271757

A GUID is 16-bytes (128-bits) written in hex

    3F2504E0 4F89 11D3 9A 0C 03 05 E8 2C 33 01

GUIDs are written using a four-byte word, 3 two-byte words, and a six-byte word, such as:

LVL 35

Assisted Solution

mrichmon earned 100 total points
ID: 16271838
In most generators they are written as SMithJW showed which is generally 32 characters excluding spaces and dashes and brackets and other divider characters.  If your generator does that then you should only need about 50 characters for the max case.  But my first post covered worst case scenario.

However, I recommend testing your generator and then going off of that.  It should be consistent each time from teh same generator.
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Expert Comment

ID: 16271871
It is safe to remove any formatting characters i beleive, as they are in the same position for every GUID... at least that was my interpretation of them, i could be wrong...
If im right though, id seperate just the meaningful data to save space.
but yeah, as richmon says, test the generator and handle it from there.
LVL 41

Expert Comment

ID: 16271874
Have you considered storing the GUID as a "GUID-type" in the database (rather than a string)?   Most databases natively support a GUID type
LVL 13

Expert Comment

ID: 16272338
As your probably aware,

System.Guid guid = System.Guid.NewGuid();
LVL 35

Expert Comment

ID: 16566225
Split SmithJW {16271757} & mrichmon {16271838} & graye{16271874} & devsolns {16272338}

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