Microsoft Acess .mdb file format

Posted on 2006-07-03
Last Modified: 2012-05-05
Hi! Everybody!

I m working on to th microsoft Access .mdb file format. where i want to know how data is stored in the .mdb file format. Is anybody help me by giving me any link at which we get the document of the .mdb file format , or we get the information how data stored in the .mdb file format. If any body know about the .mdb file format ,pls help me regarding this.
Thank You!
Question by:davinder101
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LVL 65

Accepted Solution

rockiroads earned 25 total points
ID: 17029835
Data is stored in tables, tables are like binary data in mdb
I dont know how/why u want to get data the way u do

a similar question has just been access though this talks about objects

I am not aware of any file formats as its a one file database, all objects/data held in there

It can be accessed by opening itself or thru some other language using ODBC or OLEDB to connect to it

LVL 65

Expert Comment

ID: 17029848
Have a look at MDB Tools, see if that helps u

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Assisted Solution

bluelizard earned 25 total points
ID: 17029909
from what i know, the structure of the mdb-file is not disclosed.  this is supported by this wikipedia article:

(the article is in german --- unfortunately, there's no corresponding article in the english version of wikipedia.  anyway, "Der interne Aufbau ist weitestgehend nur Microsoft bekannt." means "most of the internal structure is only known to Microsoft").

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LVL 57

Assisted Solution

by:Jim Dettman (Microsoft MVP/ EE MVE)
Jim Dettman (Microsoft MVP/ EE MVE) earned 25 total points
ID: 17030039
 The JET file format has never been documented.  From various articles, you can pick off tid bits, but no much.  What is it that your trying to accomplish?

LVL 84
ID: 17030171
I simply echo what others have said - MS has never disclosed the internal workings of the Jet database (nor would you expect them to do so). There are some very knowledgeable folks out there who recover Jet database files, and they have a much more intimte knowledge of the actual workings of Jet than do most, but they're not talking either (since they use this hard-gained knowledge to recover corrupt databases and such).
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Assisted Solution

GRayL earned 25 total points
ID: 17031585
It's called safeguarding proprietary data.  No RDBMS running on a proprietary Operating system will make its source code open.  That's a Linux/Unix mentality;-) Companies like MS and Oracle make every effort to keep the wraps on how their apps do their jobs.  

Author Comment

ID: 17036656
I try to recover data from a curropted file for this i requred how .mdb file format stores data. Is anybody have any information regarding this or link which give me information how actually data stored in .mdb file format.
LVL 57
ID: 17036770
<<I try to recover data from a curropted file for this i requred how .mdb file format stores data. Is anybody have any information regarding this or link which give me information how actually data stored in .mdb file format.>>

  You'd be better to use one of the many repair utlities/services out there:

  By the time you gather all available info, which will be by no-means complete, then figure out how to recover, you will have spent far more time then it would cost to simply use a recovery service.

  But first, try the points covered in this MSKB article:

Jim D.
LVL 65

Expert Comment

ID: 17037323
try decompiling your database
see if that just helps u get in at the very least
then try to export your data i.e. right click on a table then select export


Author Comment

ID: 17040363
Sorry Friends!
 i not rwqure any repair utlity , Bt Actualy i am trying to make a repair utlitie to repair Access File. For doing this i read the interal stracture of the .mdb file format how it actually stores data and in which manner. So if u have any information regarding the .mdb file format then try to help me.


LVL 84

Assisted Solution

by:Scott McDaniel (Microsoft Access MVP - EE MVE )
Scott McDaniel (Microsoft Access MVP - EE MVE ) earned 25 total points
ID: 17042557
Again: there is very, very little information about the internal structure of the Jet database engine. Yes, there are people who do know a tremendous amount about it (i.e. pksolutions, et al) but they aren't giving this information away.

Your best bet is to do as Jim suggested in another similar post: start by building a blank database, then use a hex editor to review this. Add a table. Review again with the hex editor, noting the changes made. Add a Text column to the table. Review again. Add a Numeric column, review again ... then add data to the columns, etc etc. The Jet Database Engine Programmer's Guide ( can give you some insight into the inner workings, but that's as close to a "spec" as you will get. It does give some information about how data is stored, but is certainly not specific. If you're serious about doing this, however, that's the place to start.

Author Comment

ID: 17079059
Hi! friends!

Thanks to give me some suggestion regarding .mdb file format.

I try to review the stracture of .mdb file format by creating two blank database then by creating tables an so on.... and then use WinHex(HexEditor) to review it but But its not work coz it show the difference in two same type of databsae file (i.e blank databaes ) and why it give this difference it is difficult to know(may be  it shows the time difference in which the database is created).

So actually to analyize the .mdb file format atleast I requred some of the information about how data is stored in .mdb file format. if someone Know about some of the bytes of .mdb file format (means what information these byte store) then pls help me .

if some one have any document that gives some of the information about the .mdb file format or any link which define some of the bytes in .mdb file format Pls try to help me.

LVL 84
ID: 17079965
Again - there IS no documentation of the way data is stored in a Jet database. The closest you will get is the Jet Programmer's Guide (at the link above). The internal structure is a proprietart and is not disclosed anywhere. Other companies who provide repair services have managed to figure out the structure, using the same basic methods as you have and a LOT of time and effort, so it must be able to be done; perhaps you could contact some of them and find out how they did this (although I doubt they're going to be terribly forthcoming with their processes).

This question is asked at times in the newsgroups as well, and Access MVPs - along with several members of the Access development team - all say the same thing - there is no document, and the only way you'll learn about the strucutre is through a lot of time, effort, and mistakes. If you don't believe what every expert here has told you, post a message in one of the Microsoft Access forums on the internet (like microsoft.public.access or
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Expert Comment

ID: 17256419
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I will leave the following recommendation for this question in the Cleanup topic area:
    Split: rockiroads {http:#17029835} & bluelizard {http:#17029909} & JDettman {http:#17030039} & GRayL {http:#17031585} & LSMConsulting {http:#17042557}

Any objections should be posted here in the next 4 days. After that time, the question will be closed.

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