ARM Club 1/ARM_CLUB_CD.iso/contents/apps/databases/progs/maxifile/instruct

Text File | 1990-04-27 | 18.8 KB | 463 lines

   Maxifile-3

       MAXIFILE

The original MAXIFILE program was written in 1985 for the BBC B to provide a
simple  database which maximised the number of records that could be handled
entirely within memory. To make the most of  limited  space,  overlays  were
extensively  used.  The  software  was used ever since for a wide variety of
purposes in a secondary school, thus  standing  up  to  the  tests  of  both
practical use and time.

When  the  Master series came on the scene, a special version was written in
128 BASIC to utilise the extra memory available in this mode. Overlays  were
no   longer  used,  partly  because  the  extra  capacity  gained  was  less
significant and partly because disc access speed was slower in 128 BASIC.

MAXIFILE-3 is the third version of the program, totally rewritten in BASIC V
for  the  Archimedes and A3000 machines. The link between the three versions
however remains, in that files are all stored in identical format  so  that,
memory  permitting,  any MAXIFILE data can be accessed by any version on any
machine.


     Special Features of MAXIFILE-3

The  vastly  increased  capacity  of  the new machines has altered the whole
concept of database size. For a 1Mb machine, the  restriction  is  now  much
more  likely  to  be  the  capacity  of  your  disc than the capacity of the
computer. The principle of all records held in RAM  is  still  followed,  so
beware  of  creating larger files than you really need - it still takes time
to load and save to disc!

Apart from increased file size, the following features are new:

1) The ability to accept field sizes up to 255 characters long.
2) The ability to create and save sub-files.
3) Improved search routines for creating sub-files.
4) All printout dated.
5) Simpler alteration of fields.
6) Provision to change discs to load or save.
7) Extensive use of mouse as an alternative to keyboard input.
8) Enhanced visual presentation.

The  program  itself  has been entirely rewritten from scratch, enabling new
features of BASIC V to be used to the full. While all the original  features
are  still  available,  some occur in different ways, and some include other
minor improvements to make them that little bit more useful.

A particular advantage of BASIC V is that with new commands like  IF...THEN,
there  is  less need to jump off into minor procedures, with the result that
the structure of the program is easier to follow.  The  result  is  that  it
becomes easier than ever to add to or modify the program to taste. Provision
was made for a routine to allow more than one page of data per  record,  but
this  has  yet  to  be written - any offers?! It is also still short of most
databases in not allowing for arithmetical calculations on fields, nor is it
written  to  take advantage of RISC-OS. Nevertheless it will hopefully prove
to be eminently usable and useful in the MAXIFILE tradition!




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   Maxifile-3

   Using MAXIFILE-3

Getting started - the Introductory Screen

The programme can be started using SHIFT-BREAK, or  by  entering  BASIC  and
CHAINing MAXIFILE3. The introductory screen offers three options: to open an
existing file, to create a new file, or to  quit.  Quitting  at  this  stage
would be cowardly, but if you must, then choose 3!

Open an Existing File

This will immediately mount the disc in drive 0, and display the contents of
the datafiles directory. Note that it  is  assumed  that  there  will  be  a
directory  $.DATAFILES  on the disc, and if you are not using a disc already
prepared for use with MAXIFILE-3 then you should set one up  before  you  go
any further.

Enter  the name of the file you wish to load. If it is not the correct disc,
then press RETURN, insert the correct disc, press any key, and  the  process
repeats.

On  entering the correct name, the file will load, and you will be presented
with the Main Menu screen.

Create a New File

Enter the number of fields that you will need. This must be  accurate  since
you  will  not  be able to change it subsequently. You are however given the
opportunity to change any errors in the next part, which  is  to  enter  the
names and lengths of these fields. Note that field lengths cannot exceed 255
characters, and the program automatically reduces any over-ambitious entries
to this limit!

After the details have been entered the computer will give you a rough guide
as to the maximum number of records it can handle. It should  be  emphasised
that  it is very rough, based on using 90% of available memory. It is likely
that you could get away with using more, but remember that your file has  to
be  saved  on disc which at most only takes 800k. If you are using a machine
with 2Mb or more, you should drastically  reduce  the  recommended  maximum.
Remember  also that a large file takes a longer time to load or save, and so
you should not set a size beyond your likely needs.

You are now presented with the Main Menu screen.

The Main Menu Screen

This menu could be called the File Menu, since  it  deals  only  with  those
functions  relating to the file or sub-file alone. Thus you may wish to view
a file, save it or print it; all other activities within  the  database  are
record  or  field  related.  The  Main  Menu  therefore  only gives you four
choices: to view, to save, to print or to quit.

View Records

This option leads you to the main record screen. As this  contains  most  of
the  important  features  it is described fully in the next section of these
notes. Briefly, you can browse through the records by using 1 for forward or
2  for  back,  or click the select button on these boxes. If you hesitate to

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try the other buttons before reading the appropriate section, then press  0,
or click on the Main Menu button, to return back to the Main menu.

Save File or Sub-File

Whether it will save the mainfile or the sub-file will depend on which Index
you are in. You start off in Index 0 which  is  always  the  original  file.
Moving into a sub-file can only be done from the Record Screen, but whenever
you exit from the Record screen you remain in whichever  file  you  were  at
that  time,  or  in  the  new  sub-file if you have just selected a new one.
Sub-files are listed as either Index 1 or Index 2.

Thus the save routine will apply to the current Index, and will  operate  in
the  same  way without regard to which file you are in. The program asks you
for the name to be used, and you can press RETURN to use the  same  name  as
before. However beware! Don't over-write your main file with a sub-file!

You  are also given the option of saving only part of the file by specifying
the first and last records to be saved. This  facility  could  be  important
when  saving  a  sub-file. The main-file might be very large, and you may be
limited on disc space. Therefore to save the sub-file  with  relatively  few
records as a smaller file could be essential. A sub-file is usually going to
be much smaller than the main file, but the defaults have to assume you want
it to be the same size.

A sub-file is saved just as though it was a normal MAXIFILE datafile, and it
can therefore be reloaded as the main file, or  can  be  loaded  into  other
earlier versions of MAXIFILE provided it is not too large.

It  is  important  to  remember  that MAXIFILE-3 will save the blank records
(filled with asterisks) as well as the valid records. This is to ensure that
sufficient  space is kept on the disc for future expansion of the file. As a
result, a large file will take longer to  save.  On  the  other  hand,  when
loading,  MAXIFILE-3  will  only load valid records, and will not waste time
loading blanks.

There is however a catch to this, namely that if you allow any blank records
to  occur  between  valid  records,  the  whole  file will be saved, but the
complete file will not be loaded subsequently. In normal  use  this  problem
should  not  arise  because the program is written to try to ensure that any
blanks are put at the end of the file. However it can happen if  you  choose
to  alter  a  blank  record  that does not immediately follow the last valid
record. If in doubt, SORT the file before saving.

Print File or Sub-File

As with the saving routines, the  print  routine  will  apply  only  to  the
current  Index.  Users  of  previous  versions  of  MAXIFILE  will notice an
important difference  here  because  there  are  no  longer  special  search
routines  included  in  the  Print  section.  This is because you can create
sub-files instead, and if you wish to access only  particular  records  then
you should create the appropriate sub-file first, and then print that.

The print routine does however enable you to select which fields you wish to
include, and in which order. Their selection should be easy  to  understand.
The  select button on the mouse can be used rather than the letter keys, and
you can use RETURN rather than the 'No more fields' option.


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The layout of the hardcopy is automatic, and depends on whether it will  fit
in  columns  or  not.  If  you have a long file that does not fit across the
page, then you might use less paper if you select fields to fit and do  more
than  one  run! A number of printer codes are included in the print routine,
and are all Epson codes. If you have a printer  than  does  not  conform  to
Epson  codes  then  you will need to do some alterations. Codes used include
underline, elite, condensed and italics.

Where possible the printout is in columns, in the largest  print  size  that
will  fit.  If  it  will  not fit in condensed, then printout is in pica (10
ch/in), and fields are printed line by line. This is obviously  more  costly
in  terms  of  paper, taking a minimum of two lines for every field of every
record.

You may choose the range of records to be printed, defaults being the  whole
file.  The  printout  is  either headed or tailed with the day and date, the
name of the file and the index number, and the number of records listed.


The Record Screen

This is the heart of MAXIFILE-3 where all alterations, additions, deletions,
selections, sorts and searches take place. There are 10 choice  boxes,  plus
additional  features  selected using the mouse. At the top of the screen the
filename appears, the maximum number of records the file is set up to  hold,
and the current Index number. The record number also appears top right.

Next

Simply  click  select  on  this  box,  or press '1' (or even press SPACE) to
display the next record in the file. If you do so  while  viewing  the  last
record then you will return to the Main Menu.

Last

Select with the mouse or press '2' to go back to the previous record.

Delete

If you are in Index 0 (i.e. the main file) then this routine will delete the
record entirely, although the record will not of  course  be  lost  on  disc
until you save the revised file. If you are in a sub-file then the record is
deleted from the sub-file only.



Insert

You can only add new records if you are in Index 0. The program makes  space
for  a  new record to immediately follow the record you had been viewing. If
by so doing it would lose the last record in the file you will be warned and
given  the  option  to  abort  the  insert  routine.  The new record is then
presented as a blank record on screen - i.e. made up of asterisks - and  you
must  then  select  the  Alter box (explained below) to enter details in the
fields. This is important because if the first record is left with a leading
asterisk,  then  data could be lost after saving. (See the note on saving on
page 3 for further explanation.)


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   Maxifile-3

Main File

DO NOT CONFUSE THIS with Main Menu! This enables you to move up a  level  in
the Indices. Thus if you are in Index 1, this will move you back to the Main
File which is Index 0. If you are in Index 2 then you will move to Index  1.
Whatever  index  applies,  you  will  be  returned  to  the  Main Menu after
selecting this choice, but remember you are  now  in  a  higher  index  than
before  (unless  of  course  you  were  already in 0!). The opposite of this
selection can only be achieved by using the menu button on the mouse.

Sub File

This is not the true reverse of main File because it  automatically  assumes
you  wish  to set up a new sub-file. NB: Once you have selected this option,
you have lost your previous subfile at the next lower level if if previously
existed.

It  may  help to understand how this part of the program is devised. You are
given an opportunity to set two conditions, but each  condition  is  set  up
separately,  and  only  then do you tell the program how you wish to combine
them. You do not have to set both conditions, and the program deals with the
first  condition  completely  before  it  asks  if  you want to set a second
condition.

To set up a condition you must first identify the field it relates  to,  and
then  the string within that field with which a comparison will be made. You
may then require the field in each record to be greater than  or  less  than
the  chosen  string,  to contain the chosen string, or to exclude the chosen
string. Following this choice you are then asked if you  want  to  impose  a
second condition.

If  you  choose a second condition then it is set in exactly the same way as
for the first, but having set up the condition you are then  asked  how  you
wish  to  combine them. The first option is to combine the two conditions so
that all the selected records of both operations are combined together - the
Inclusive  Or.  The  second  'Not Both' is the Exclusive Or - Condition A or
Condition B but not any records that are included in both. Only both is  the
logical  AND,  and  sets  up  the  sub-file  with  records that satisfy both
conditions. If you are familiar with set theory a venn diagram may help!

This method of creating a sub-file should enable all two-condition tests  to
be  satisfied.  If  you  need  to  impose  a  third condition, then set up a
sub-file of the sub-file - this is what Index 2 is there for.

Sort

This routine enables you to  make  a  primary  sort  on  one  field,  and  a
secondary  sort  on a second field if required. You may sort in ascending or
descending order. The coding is based on a simple bubble sort,  but  on  the
Archimedes this still gives an acceptable speed for most purposes. Note that
the sort only applies to the current Index.

Go To - Including Replace

At its simplest you select 'Number of Record Required' and enter the  number
of  the  next  record  you wish to view. This is particularly useful to move
about quickly in a large database rather than going through one at a time.


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   Maxifile-3

The 'Field search' option has two purposes. You can use it simply  to  reach
the  first  record  with the field containing the chosen string by selecting
'View' - but that is all it does. Remember that this is  essentially  a  'go
to' routine, but if you want ALL the records that contain the string you can
set up an appropriate sub-file.

There is however a much more important replace option linked to Field search
which  will  replace  all  occurrences of the chosen string with a specified
second string.

Print

This enables you to obtain a printout of the record currently displayed.  No
choices  are given, and it always prints in block rather than column format,
but it does date the printout and record the file name and record number.

Main Menu

Self-explnatory, really!

Alter record

This is only selected using the SELECT mouse button on the black  box  close
to  the  top  of  the  screen. It is however the main method of entering new
data, and it expects you to enter information consecutively into each  field
in  turn.  At  the  start the first field is hilighted and the length of the
field is picked out by a white line. If you type beyond this, the entry will
be  truncated  to  the  maximum  length.  When  you  press  return, you will
automatically move to the next  field,  and  so  on  until  all  fields  are
completed.  If a field already contains correct information, pressing return
on its own will restore the original contents.

Alter a Field

Fine adjustment or the complete replacement of just one field could be  done
using  the  Alter Record routine, but this is not always convenient. You may
for example wish to keep on screen the  existing  field  contents  and  just
modify  them  slightly.  To  do  this  press  the ADJUST button on the mouse
against the field name. The name will change colour, and a correction window
appears at the top of the screen containing the field contents.

You  can  alter the contents of the window using the cursor keys to position
the cursor, or using SELECT on the mouse to position the  cursor  where  you
need  it.  If the field is too long to fit in this window, then you must use
the cursor keys to move the hidden part into view. At  the  cursor  you  may
type  in new text (which pushes old text to the right, but may loose the end
of the contents that no longer fit within the field length), use  DELETE  to
delete  left,  use  COPY  to delete right (i.e. above the cursor), CTRL-U to
delete the whole field content, or ESCAPE  if  you  decide  to  abandon  the
correction!  RETURN  however will replace the field content with the revised
entry.

Move into an existing Sub-File

Use the MENU button on the mouse to select the  next  Index  down,  assuming
that it has already been defined. This will return you to the Main Menu, but
in the new Index.


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   Maxifile-3


Improvements

No  software  is  complete, and there are several enhancements that could be
made to this program. Some are listed below. Offers to write the appropriate
routines would be welcomed!

I  would  like  to  include  some  arithmetic facilities, chiefly an average
routine and a total routine.

There should be a routine to  add  extra  fields,  or  to  delete  fields  -
particularly from sub-files.

Other routines to convert data into an InterWord file which can then be used
for mail merging (on Masters and Compacts, anyway) already exist. A  routine
could be written however to at least print envelopes!

How  about  providing alternative layouts of the Record Screen? Possibly not
showing all fields? A constraint here is the file  storage  format  on  disc
which  has  deliberately  been  kept  compatible  with earlier versions, but
screen formats could possibly be saved separately.

Print formats designed on screen.

This is not a RISC-OS program - will MAXIFILE-4 be the next step? Not unless
there are more rainy days than usual, or someone writes it for me!




CALW
April 1990



























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