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dbRX version 1.04 Users Manual
Manual Last Updated July 8, 1993
Copyright (C) 1993, by Gerald P. Doyon
All Rights Reserved
dbRX v1.04 User Documentation
▓▒░ SOFTWARE REGISTRATION ░▒▓
──────────────────────────────────────────────────────────────────────
dbRX version 1.04 has been released to the public at no cost for
un-limited PERSONAL use. All subsequent versions will not
necessarily be free.
The following statement applies to companies who wish to bundle
this software with their own, or other proprietary software
*****
dbRX is copyrighted (C) 1993, by Gerald P. Doyon and is
protected by United States Copyright Law and International
Treaty provisions. All rights are reserved. Non-registered users
of dbRX are licensed ONLY to use the program on a EVALUATION basis
for the sole purpose of determining whether or not it meets
their requirements. All other use requires registration.
Any other use of non-registered copies of dbRX by any person,
BUSINESS, CORPORATION, OR GOVERNMENT ORGANIZATION, or any OTHER
entity is strictly forbidden and is a violation of this license
agreement.
Registration permits a user a license to use dbRX on a single
computer.
dbRX may NOT be distributed in conjunction with any other
product, hardware or software without the express written
permission from Gerald P. Doyon.
dbRX v1.04 User Documentation Page 02
▓▒░ WARRANTY ░▒▓
──────────────────────────────────────────────────────────────────────
Gerald P. Doyon makes no warranty of any kind, expressed or implied,
including without limitation, any warranties of merchantability and/or
fitness for a particular purpose. Gerald P. Doyon shall not be liable
for any damages, whether direct, indirect, special or consequential
arising from a failure of this program to operate in the manner desired
by the user. Gerald P. Doyon will not be liable for any damage to data
or property which may be caused directly or indirectly by use of the
program.
IN NO EVENT WILL GERALD P. DOYON BE LIABLE FOR ANY DAMAGES, INCLUDING
ANY LOST PROFITS, LOST SAVINGS OR OTHER INCIDENTAL OR CONSEQUENTIAL
DAMAGES ARISING OUT OF YOUR USE OR INABILITY TO USE THE PROGRAM, OR FOR
ANY CLAIM BY ANY OTHER PARTY.
dbRX v1.04 User Documentation Page 03
▓▒░ TABLE OF CONTENTS ░▒▓
──────────────────────────────────────────────────────────────────────
Registration . . . . . . . . . . . . . . . . . . . . . . . . . . 02
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . 03
This Page !. . . . . . . . . . . . . . . . . . . . . . . . . . . 04
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 05
How dbRX Works . . . . . . . . . . . . . . . . . . . . . . . . . 06
dbRX At Work . . . . . . . . . . . . . . . . . . . . . . . . . . 07
Test Driving dbRX. . . . . . . . . . . . . . . . . . . . . . . . 08
What's Next ?. & Suggestions Welcome . . . . . . . . . . . . . . 08
Revision History & How To Contact The Author . . . . . . . . . . 09
dbRX v1.04 User Documentation Page 04
▓▒░ INTRODUCTION ░▒▓
──────────────────────────────────────────────────────────────────────
dbRX was developed from a need to repair corrupted database files
quickly, without having to go through numerous steps in order to
get your application back up and runnning.
dbRX is FAST ! On my computer I can repair almost 30 databases in
approximately ONE SECOND. No user intervention is needed after
dbRX has started. There are no menus to flip through. dbRX makes
one pass through each database.
Unlike several other database repair utilites, dbRX does not
reconstruct/re-write the records contained in the database. The
vast majority of databases are corrupted only in it's header.
The header contains info pertaining to such things as the type of
the database, how many records are in it, where the data begins,
etc. More information concerning the header will be explained
futher in this manua. By repairing the header only you can be up
and running in seconds, literally !
Database Types Supported
------------------------
dbRX, at this time, can only repair the following database types:
dBASE III Plus & dBASE IV
FoxBASE+
FoxPro
Although database files created by Clipper are for the most part
compatible I cannot guarrantee dbRX will work flawlessly with them.
I am working on getting sample clipper files and associated
structure breakouts to better repair them.
What dbRX CAN do:
-----------------
- Repair an invalid total record count in DBF header
- Replace missing End-Of-File character
What dbRX CAN'T do (Yet!)
-------------------------
- Does not repair record data corruptionm
- Does not go through every item in the header of the DBF
to check for invalid data or inconsistencies
dbRX v1.04 User Documentation Page 05
▓▒░ HOW dbRX WORKS ░▒▓
──────────────────────────────────────────────────────────────────────
To run dbRX simply type the following at the DOS prompt:
DBRX <filename>
where 'filename' is the name of the database file you wish to
repair. The filename can include a path AND wildcards. For
instance these are all valid examples:
EXAMPLE #1: DBRX INVENTRY.DBF
EXAMPLE #2: DBRX C:\FOXPRO\DBFS\INVENTRY.DBF
EXAMPLE #3: DBRX C:\FOXPRO\DBFS\INV*.DBF
EXAMPLE #4: DBRX D:\FOXPRO\DBFS\INV?????.DBF
EXAMPLE #5: DBRX D:\FOXPRO\DBFS\*.DBF
EXAMPLE #6: DBRX *.DBF
I think you get the idea now ! dbRX does NOT assume a file
extension of '.DBF' if you do not enter one. Consequently the
database file may have ANY extension you wish !
Through my own experiences I have found that nearly all of the
database files that have become 'corrupted' are damaged only in the
database files header, NOT in the actual data records.
A database file can be broken up into three sections:
1. Data File Header Record
2. Field Subrecords
3. Data records
When a database becomes corrupted, in MANY instances, the total
record count in bytes 04-07 of the header does not match the actual
number of records in the database.
This can occurr if a new record is added to the database but
the header has not been updated to reflect the new record count,
possibly due to a power failure, disk error, etc..
In this instance it is very easy to correct the problem. You need
only determine the actual number of records in the database and
overwrite the incorrect one.
After a database record has been added an end-of-file (EOF)
character is appended, CONTROL-Z, or 01A hex. dbRX will make sure
this character is present. If it is not one will be appended.
dbRX v1.04 User Documentation Page 06
▓▒░ dbRX AT WORK ░▒▓
──────────────────────────────────────────────────────────────────────
Assumptions Made:
-----------------
As of this release dbRX assumes that atleast the very first byte of
the databases header has not been corrupted. The DBF files first
byte, which contains the DBF type, i.e. Foxpro, dBASE, etc, must
NOT be corrupted. Also, the record size also cannot be corrupted.
If after dbRX reads in the first 32-bytes and a VALID DBF type was
not found the program will end.
I used a HEX editor and corrupted a bunch of DBF's that came with
FoxPro. I then invoked dbRX using the following syntax:
DBRX *.DBF
This was the result:
╓────────────────────────────────────────────╖
║ ■■ dbRX v1.04 ■■ ║
║ ║
║ Copyright (c) 1993 by Gerald P. Doyon ║
╙────────────────────────────────────────────╜
CARDUSER.DBF - Repairs made:
End Of File Marker Appended
CLIENTS.DBF - Ok
CREDCARD.DBF - Ok
DETAILS.DBF - Repairs made:
Total Record Count Adjusted
FACTORS.DBF - Ok
LABELS.DBF - Ok
LETTERS.DBF - Ok
ORGHELP.DBF - Ok
ORGUSER.DBF - Ok
PERSONAL.DBF - Repairs made:
Total Record Count Adjusted
End Of File Marker Appended
REPORTS.DBF - Ok
RESTAURS.DBF - Ok
STATES.DBF - Repairs made:
Total Record Count Adjusted
UNITS.DBF - Ok
C:\TASM\DBRX\TEST>
As you can see, a simple report is generated for each item that is
repaired. If no repairs were necessary then an 'Ok' is reported.
If a file/disk error occurs while dbRX is in the process of reading
or writing to disk dbRX will halt and report the type of error that
occurred.
As of this version dbRX does NOT return an error code that can be
used in batch files. The NEXT version due out VERY soon will do
that.
dbRX v1.04 User Documentation Page 07
▓▒░ TEST DRIVING dbRX ░▒▓
──────────────────────────────────────────────────────────────────────
I have included a corrupted database file, BAD_DBF.DBF, which has
an invalid record count and missing end-of-file marker. First,
attempt to access this database with either dBASE, FoxBase, or
Foxpro. Of course, you will be unable to do so. Now use dbRX to
repair it:
dbRX BAD_DBF.DBF
Voila, it has been repaired ! Now you can access the data.
▓▒░ WHAT'S NEXT ?? ░▒▓
──────────────────────────────────────────────────────────────────────
- In the next version, due out soon, dbRX will return error codes
so that you can use it in a batch file type operation.
- The ability to BACK-UP and RESTORE a DBF header in the event of
a masssivly corrupted header that can't be repaired. This will
then allow you full access to your otherwise un-recoverable data.
- Several cosmetic enhancements.
Suggestions ???!!!
------------------
Since the first public release of dbRX is free I would really
appreciate some input, good OR bad, in lieu of money. I welcome ANY
suggestions on how I might improve dbRX ! If your suggestion is
implemented I will give you credit for it in this documentation.
dbRX v1.04 User Documentation Page 08
▓▒░ REVISION HISTORY ░▒▓
──────────────────────────────────────────────────────────────────────
05/13/93 v1.0 - Not released to public. Allowed user to
only repair one DBF at a time.
05/16/93 v1.01 - Optimized several routines for best speed.
05/22/93 v1.02 - Cleaned up more code. Made dbRX easier to
add numerouse features. Added ability to
use paths.
06/01/93 v1.03 - Added ability to use wildcards.
07/08/93 v1.04 - After a small siesta the documentation was
written and some text output cleaned up.
First release is FREE to the public !
How To Contact the Author
-------------------------
You can leave message for me, GERRY DOYON, on the Northern Lights
BBS, located in Maine, at the following numbers:
Node #1: (207) 761-4782 2400 baud (Public line)
#2: (207) 761-4565 HST D/S v.32/v.42bis
#3: (207) 761-4540 9600 bps USR Courier HST (opens at 19,200)
#4: (207) 761-4431 9600 bps USR Courier HST (opens at 19,200)
Nodes 2-4 are for subscribers only. As a new caller you are
allowed 15 minutes per day with all priveleges accept downloading.
The most current version of dbRX will always be uploaded to the
Northern Lights BBS first.
You can try to contact me via the U.S. mail at:
Gerald P. Doyon
P.O. Box 133
Westbrook, ME 04098-0133
Or at home, (207) 854-2906 between 6:00pm to 11:00pm EST.
Unfortunately, I do not have a Compuserve or GEnie account.
dbRX v1.04 User Documentation Page 09