DB3ISO
1. Background and documentation
DB3ISO was written in 1987 by a certain Alejandro, probably
from Cuba, in the 8086/88 assembler language. It is an
executable file (in fact a ".com" file), that converts dBase
III and dBase III+ files into the ISO 2709 structure.
The program is documented in an English and in a Spanish
manual, but the English is of a rather poor quality.
Related to this program is ISODB3, by the same author. ISODB3
converts ISO 2709 files into the dBase structure.
2. General evaluation
Plus
DB3ISO is easy to use for straightforward conversions.
- It may outlimit other conversion programs in speed.
- It allows you:
- to break up some source fields into occurrences
of one CDS/ISIS target field
- to make a repeated CDS/ISIS field out of the
content of different dBase fields
- You can select which fields to convert.
- You can limit a scope of dBase records to convert.
- You can renumber the records.
- The program skips deleted dBase records.
- It can handle memo fields and files created with recent
dBase versions.
- DB3ISO uses conversion tables which look very much like the
CDS/ISIS field selection tables (FST), which is a technique
- familiar to CDS/ISIS users.
Minus
DB3ISO does not display the dBase structure: you will need another tool to analyse it.
- It does not allow you to replace, delete or add strings.
- The program does not offer any tool to create the necessary conversion tables; you must use an editor to do so.
- It overwrites target files without any warning.
3. Preliminary work
Before starting the conversion it is necessary that you
analyse the structure of the input file. This can be done
using dBase commands or through the use of a dBase "viewer"
(see paragraph 6.6.).
This will produce an output like this:
Structure for database: C:books.dbf
Number of data records: 0
Date of last update : 11/14/95
Field Field Name Type Width Dec
1 AUTHOR1 Character 30
2 AUTHOR2 Character 30
3 AUTHOR3 Character 30
4 TITLE Character 50
5 PLACE Character 30
6 PUBLISHER Character 30
7 PAGES Character 10
8 ILL Logical 1
9 ISBN Character 14
10 KEYWORDS Character 50
** Total ** 275
(This is not the structure of an existing bibliographic dBase
file, which might be up to 30 or 50 fields long.)
It is recommended to browse the input file in order to see if
there are fields
- which are in fact repeating
- or which should form occurrences of one field in the target file
Record No. 1
AUTHOR1 Willis, Joe D.
AUTHOR2 Freye Campbell, Linda
AUTHOR3
TITLE Exercise psychology
PLACE Champaign
PUBLISHER Human Kinetics
PAGES xi, 258
ILL Y
ISBN 0-87322-366-7
KEYWORDS psychology; fitness; physical education
In this example the fields AUTHOR1, AUTHOR2 and AUTHOR3 should
form one CDS/ISIS field in the end, and the field KEYWORDS
must be split up into 3 occurrences of one CDS/ISIS field.
This can be done by the means of a FST, which has to be made
with an editor. The general structure of this kind of FST is:
target field numbering FST technique dBase numbering
1 0 v1
In the case of the example used here, the FST may look like
this:
1 0 v1
1 0 v2
1 0 v3
2 0 v4
3 0 v5
4 0 v6
5 0 v7
6 0 v8
7 0 v9
8 0 v10 |;|
The program will read this like:
- put the contents of dBase fields 1, 2 and 3 into ISO 2709 field 1
- put the contents of dBase field 4 into ISO 2709 field 2
- put the contents of dBase field 5 into ISO 2709 field 3
- put the contents of dBase field 6 into ISO 2709 field 4
- put the contents of dBase field 7 into ISO 2709 field 5
- put the contents of dBase field 8 into ISO 2709 field 6
- put the contents of dBase field 9 into ISO 2709 field 7
- put the contents of dBase field 10 into ISO 2709 field 8 and break it up into 3 occurrences, using the ";" as occurrence delimeter
Note that the content of different fields can be put into one
target field by using the same target numbering. Note also
that the occurrence delimiter of the source file (see last
line) must be put between | (= ASCII 124).
4. Executing the program
DB3ISO can be started with the command at the DOS prompt
db3iso
You will now see this text:
dBASE III to ISO exporter utility.
ver 2.70, written by Alejandro, 3/1987.
Select: [E]xport, e[X]it >
The program will ask some questions, which may be answered by
typing the appropriate information. In some cases you can
answer by a simple <return> to indicate that you accept the
default options the programs suggests.
The questions to be answered are:
- what is the name of the source dBase file?
- what is the name of the target ISO 2709 file?
- what is the name of the FST with the conversion specifications?
- which field separator do you want to use?
- which record separator do you want to use?
- at which dBase record do you want to start?
- at which dBase record do you want to end?
- from which record on do you want to renumber?
It may be best to accept the defaults for the 4th and the 5th
question; otherwise you will have to alter the default values
in the CDS/ISIS menu xYISO when you import the ISO 2709 file
into your CDS/ISIS database. Question 6 and 7 allow you to
make a selection to try out the conversion. It is always
better to experiment with 10 or 100 records rather than with a
database of 10,000 records... If you do not enter a record
number to start or end with, the program will automatically
fill in "1" for "Starting record" and the number of the last
record for "Last record".
You can only renumber the records when your FST contains a
line like this:
1 0 MFN
This means that the dBase record number will be stored into
the ISO 2709 field no. 1. Normally this numbering will start
at 1, but DB3ISO allows you to change that. Probably this was
meant for databases in which the CDS/ISIS records were updated
from the original dBase file.
This is an example of a filled out screen:
c:>db3iso
dBASE III to ISO exporter utility.
ver 2.70, written by Alejandro, 3/1987.
Select: [E]xport, e[X]it >E
dBASE III file name [.DBF]:books
books.DBF
Output ISO file [ISO.MST]:books.iso
books.iso
Input Field Selection Table file [.FST]:
Field separator [#]:#
Record separator [#]:#
Starting record [ 1 ]:
Last record [ 100 ]:
Renumber from:
100 record(s) exported.
Select: [E]xport, e[X]it >X
End of running.
(The input made by the user is printed bold printface; if you
do not fill anything in, the program will take it's default
values. In practice the screen does not look as nice as this.
The program does not clear the screen; it start at the actual
position of the cursor.)
When the dBase file contains a memo field, the program will
automatically locate the corresponding text file (".DBT") in
which the contents of the memo fields are stored:
dBASE III file name [.DBF]:books
books.DBF
books.DBT
5. Pitfalls
Three types of dBase fields cause problems: numeric and
logical fields.
In a dBase file numeric fields normally are preceded with
blanks. These blanks will also be found after the conversion
in the output. You can avoid this by editing the structure of
the dBase source file with dBase (or another dBase-like
software). You will need two steps to do so:
- alter the nature of the field from "numeric" into "character":
- delete the preceding blanks with this command
replace all [name of field] with ltrim([name of field])
Logical dBase fields can be filled in with "Y" or "T" for
"true", or with "N", "F" or nothing if not true. In the later
case dBase will leave a question mark. A common example of a
logical field in a bibliographic database is a field where one
can register if a book contains illustrations:
ILL Y
When not filled in, this question mark will be transformed by
DB3ISO into a space. You can solve this problem in two ways:
- Before the conversion: make sure that the
dBase field always contains "N" when "not
true" is meant. This can be done with the
command
replace all ill with .N. for .not. ill
- After the conversion: import the ISO 2709
with a FST that contains a statement like
this:
if v8='Y' or v8='T' then '^bill' fi
Both 'Y' and 'N' must be taken into account, because:
- you do not always know what was filled in and
- DB3ISO does not check the content of the logical field.
Date fields on the other hand do not cause problems. They are
converted into the ISO form: YYMMDD, e.g. 19960130 for 30
January 1996.
6. Recommendations
DB3ISO allows you to make a few modifications. The purpose of
this technique is to convert the source file into a format as
close a possible to the structure of the target CDS/ISIS
database. A FST like this
200 0 v4
300 0 v1
300 0 v2
300 0 v3
etc. is meant to introduce the field tags of the Common
Communication Format (CCF), in which 200 stands for the title
field and 300 for the author field. After this, you can
import the ISO 2709 file into your database without further
modifications.
But it is better not to do so. Use the numbering of the source
field as long as possible, which probably results in not using
any conversion table for DB3ISO. Experience shows that in most
cases you still need an FST when you import the file. You can
use this FST to add some information that was not in the dBase
file, e.g. the date of the conversion. Then it might become
tricky to make a distinction between the original numbering,
the ISO 2709 numbering and the CDS/ISIS tags.
A FST for the example we used here may look like this:
22 0 '^a19960210'
100 0 "^a"v9
200 0 "^a"v1/,"^a"v2/,"^a"v3/
300 0 "^a"4
400 0 "^a"v5,"^b"v6
460 0 "^av7" p", if v8='Y'or v8='T' then '^bill' fi
620 0 "v10
(We assume the CDS/ISIS database uses the CCF tags.) After the
conversion the ";" of the keyword can be transformed into the
occurence delimiter "%" with a CDS/ISIS modification program,
e.g. GMOD. The "," in the author field may be changed to "^b"
by the same kind of program.
© Piet de Keyser, 1998
Piet de Keyser's Manual Collection