==== DOCUMENTATION FOR UNIQUE.CMD (C) ====

                           Version 2.4
                       Released 12/16/1987

        A dBASEII(tm) Utility To Purge Duplicate Records
                  From a dBASEII(tm) .DBF file

                               by
                         James A. Gronek
                        Phoenix, Arizona
                                &
                        Stephen Aidikonis
                      Streamwood, Illinois

                     COPYRIGHT (C) UCS, inc.
                        1984, 1985, 1987
                       ALL RIGHTS RESERVED

              dBASEII is a trademark of Ashton-Tate

                   Incorporates routines from:

            DATEIN.CMD (c) 1983 by Bernard L. Lambert
               SHRINK.CMD (c) 1984 by Les Shockley

                    ====  WHAT IS IT??  ====

     UNIQUE.CMD  is  a utility program that is designed to  allow
you  to purge almost ANY dBASEII .DBF file of duplicate  records.
It  is written in the dBASEII applications language and  requires
dBASEII version 2.4 or later to run on any  computer.  UNIQUE.CMD
may be used with any database that has character fields to use as
keys.   It  creates  a  file,   UNIQUE.DBF,   that  contains  the
unduplicated  records of your original source database.  Once you
have verified the validity of UNIQUE.DBF,  you may rename it  for
use  in  place of your source database.  It will not  alter  your
source database in any ANY WAY!!

                  ==== HOW DO I USE IT?? ====

     Place DBASE.COM,  DBASEOVR.COM, and UNIQUE.CMD together with
the database you wish to purge. Ensure that you have a blank disk
in  the default drive,  or sufficient space on the disk with your
database  to allow for working room.  See the discussion on  free
space requirements later under TRADEOFFS.

     When  you execute the program ( A>DBASE  UNIQUE<CR>  ),  you
will be prompted for a system date,  and a default drive.  If you
do  not have sufficient space on the same disk with your original
database,  select a disk with sufficient space for working  files
and the database of unique records, UNIQUE.DBF.

     Next, you will be presented with a list of the .DBF files on
your default disk, and asked to select the database to be purged.
If you selected a blank disk as your default drive, no files will
be  listed.  Enter the PRIMARY FILENAME of the .DBF to be  purged
(including the drive, if not on the default disk).

     After some status messages, you will be shown a selection of
character fields in your .DBF and asked for an index key.  Select
the field names to be used for comparison,  one at a time. Ensure
that  you  select a sufficient number of fields to compare on  to
guarantee  record  uniqueness.  Watch out that you  don't  exceed
dBASE's  internal limits of 99 characters in your index  key!  If
you do, you will be unceremoniously dumped to a dot prompt.

     As  you  enter the field names to be used,  you will  see  a
status line appear on the bottom line of the screen,  showing the
syntax  of  the  index key you are  constructing.  It  will  look
something like this:

          FIELDNAME1+FIELDNAME2+FIELDNAME3+FIELDNAME4 ...

     You may select on up to FIVE separate fields so long as  the
combined  length  of the fields does not exceed the 99  character
limit.  When  you  have entered the last field name to  be  used,
enter a <RETURN> to continue.

     You  will be presented with a choice of two ways  to  attack
the problem.  You may select either "A" or "B" from the menu. See
the section following:

                      ==== TRADEOFFS ====

     The   two   methods  used  to  purge  the  database   differ
dramatically.  Selection "A" uses a technique that is very MEMORY
VARIABLE  DEPENDANT and can only be used on databases with 22  or
fewer  total  fields.   The  purge  function  will  begin  almost
immediately,  but  proceeds  SLOWLY from there,  on through  your
database.  This method requires less free disk space to use  than
method "B", described next, but can take as much as TWICE as long
to run as method "B".

     Selection "B" uses a technique that requires the indexing of
the  source database on the index key before starting the  actual
purge  function.  This  can  take  varying  amounts  of  time  to
accomplish,  depending  on  the number of records in  the  source
database,  and  the complexity of the index key.  About the  only
thing  I can tell you is that it will ALWAYS seem to take  longer
than  it should.  Once the Purge has started,  the program fairly
RIPS through the database, about as fast as a terminal can update
the  count on the screen,  faster in some cases.  This method  is
extremely DISK SPACE DEPENDANT.  IN ORDER TO ENSURE A  SUCCESSFUL
RUN YOU SHOULD HAVE,  AT LEAST, FOUR (4) TIMES AS MUCH FREE SPACE
AS  THE  SIZE OF THE SOURCE DATABASE!!!  If you are running on  a
hard disk, you have no problems. Those on floppies may run out of
room with larger databases.  This method can be (by my  benchmark
tests, anyway) up to 2.5 times as fast as method "A".

     So,  which one should you use?  It depends on your database.
If  you  have a small database (few records) then  selection  'A'
will  probably  be faster,  overall.   You will not have to  wait
while UNIQUE constructs an index file on your database.

     If,  on the other hand,  you have a database of 300 or  more
records,  'B' is your best bet.   It starts slower, but runs MUCH
faster through longer databases, than the 'A' routine.

     During  the time the program is processing your source .DBF,
status messages will be sent to the console advising you of  what
record numbers are under study at any given time.

               ====  KNOWN BUGS AND CAUTIONS ====

     UNIQUE.CMD  is  NOT fast.   It is written  entirely  in  the
dBASEII applications language and is intensely disk-bound, hence,
very slow.   Despite its 'underwhelming' speed of execution,  its
flexibity  may  make it a valuable addition to the dBASEII  users
'Toolkit'.

           ====  VERSION 2.0 UPDATE INFORMATION  ====

     This  release of UNIQUE.CMD incorporates  many  improvements
over  the  original  version,  primarily due to  the  efforts  of
STEPHEN  AIDIKONIS of Streamwood,  Illinois.  Steve came up  with
error  checking routines that greatly improved the key  selection
routine.  He  also  came  up with TWO  different  (and  superior)
methods  to  do  the purge function.  I studied and  tested  both
before  deciding  that each had its' own  merits,  and  potential
applications.    Well,  they  are  both  incorporated  into  this
version,  you may select from them as appropriate.  Thanks Steve,
your efforts made a useful tool into an indispensible one.

           ==== VERSION 2.1 UPDATE INFORMATION ====

     This release repairs a 'bug' found in the (A) search routine
and  incorporates some additional changes to reduce the  size  of
the .CMD file.

           ==== VERSION 2.2 UPDATE INFORMATION ====

     This release is functionally identical to version 2.1,  with
the exception that default drives may be in the range "A" through
"P".  This  modification  was made at the request of  some  users
without  contiguous  disk drives.  Version 2.2 also  incorporates
some  additional changes to reduce the size of the command  file,
and speed execution.

           ==== VERSION 2.3 UPDATE INFORMATION ====

     This release incorporates NUMEROUS coding changes, mostly to
eliminate unnecessary or redundant commands, and correct a couple
of  minor display bugs.   Version 2.3 is,  again,  released as an
encoded  file.   With the plethora of Public  Domain  Uncrunchers
available,  I  hold  no illusions concerning the security of  the
file.   The 'uncrunched' file will indeed demonstrate the  coding
techniques used,  but, they will be unintelligable to all but the
most  sophisticated  of  dBASE  programmers  without  the  source
comments.


            ==== VERSION 2.4 UPDATE INFORMATION ====

     This   release  of  UNIQUE  adds  a  routine  to  check  for
apostrophes or double quote marks in the index key string.  Early
versions  would crash if a double quote mark (") was imbedded  in
the index key string.   Also,  early versions would not accept  a
date  later  than  1985.   This release will not  accept  a  date
earlier  than  1987.   There  have  been changes  made  to  speed
execution and shrink the size of the code.


                    ====>>>> WARNING <<<<====

     Finally,  this  program is COPYRIGHTED.  I wrote it.*  I  am
releasing it to the Public Domain for non-commercial use by other
people  who  may  find  it of use.  This program  may  be  freely
reproduced  and  distributed,  as  long  as  this  file  and  all
copyright notices remain intact and no monetary consideration  is
involved.

(*  versions  2.0  &  2.1  co-authored  with  Stephen  Aidikonis,
Streamwood, Ill.)

     UNIQUE.CMD  is being distributed as an encrypted  file.  The
file occupies less  space on  the disk,  and executes faster,  in
this  form.   The  .CMD file cannot  be  listed,   or  externally
altered.  I  have attempted to compile UNIQUE,  using  WordTech's
dBASEII Compiler, but the compiler is not sophisticated enough to
allow  the  use  of macros such as those used  in  UNIQUE.  Fully
commented Source  code  is available from the author.

     If  you modify the program,  I forgive you.  Please upload a
copy  of  the modified code to me at my RCP/M (see  below)  as  a
'PRIVATE' file, and PLEASE keep the source code to yourself. If I
decide to incorporate your modification in a future revision, you
will receive appropriate credit in the documentation.

     If  you  desire an 'Official' copy of the  commented  source
code,  you may purchase it for $15.00,  if you pick it up from my
RCP/M, or for $25.00 on 5 1/4" disk by return mail. I can support
about  50  different  formats,  leave a message on my  RCP/M  for
information of disk formats.  Money Order or Cash orders will  be
shipped  within  48 hours.  Allow 2 weeks for personal checks  to
clear.

JAMES A. GRONEK
President UCS, inc.

Telephone:

The  Lost Dutchman's Gold Mine PICS
(602)247-2880 300-1200-2400 Baud
24 Hours 7 Days a week

Address:

The Lost Dutchman's Gold Mine PICS
Post Office Box 23937
Phoenix, Arizona 85063

Attn: Unique