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1992-11-12
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PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 1/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
This Technical Information sheet discusses common questions and
answers on Paradox 4.0 and BLObs. For information on how to
import BLObs into Paradox fields, refer to Question 5 of this
Technical Information sheet.
1. Question:
What is a BLOb? And what can I store in a BLOb
field?
Answer:
BLOb is an acronym for Binary Large Object. It is
the type of data that you store within a binary field in
Paradox. The new binary field type in Paradox 4.0 allows
you to store nearly any type of data within a Paradox
table. By using your own editor, you specify how the data
is to be treated. Among the many possibilities are
graphics, sound, word processor documents, spreadsheets
and multimedia files. The primary considerations when
choosing what type of data to store in a BLOb field are
what program(s) are available for handling that type of
data and how much disk space is required to store that
data. A final consideration is that the BLOb editor you
choose should not be dependent on the file extension. The
reason for this is that Paradox will write the BLOb to a
file named $ZMEMZ$.ZZ when you invoke your BLOb editor.
2. Question:
Does Paradox have its own built-in editor for BLObs?
Answer:
Unlike memo fields, Paradox does not have an internal
editor for BLObs. By linking in your own editor, you have
greater flexibility and control over how your data is
interpreted and maintained. This lets you use programs
written by people who specialize in dealing with the type
of data you choose.
For example, if you want to store spreadsheet data in
your database, you could use Quattro Pro as your BLOb
editor. If you want to store word-processor data in your
database, you could use WordPerfect as your BLOb editor.
PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 2/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
If you want to store graphic images in your database, you
1
could use VPIC as your BLOb editor.
3. Question:
How do I link a BLOb editor into Paradox?
Answer:
A BLOb editor is linked into Paradox in the Custom
Configuration Program (CCP). To run the CCP, you must be
in Main mode, select the System Menu by pressing Alt-
Space, select Utilities, then select Custom. From the CCP
menu, select PAL. From the PAL dialog Box, move the
cursor to the BLOb Editor text box, then enter the name of
your BLOb editor followed by an asterisk (*). It is
generally recommended that you specify the full path name
of the editor, if possible, or take steps to insure that
its directory is in your DOS path. The asterisk at the
end tells Paradox to pass the name of the file stored in
the current BLOb field to the BLOb editor. For example,
to link Quattro Pro as the BLOb editor, you could type the
following:
c:\qpro\q.exe *
The final step is to save this configuration. Choose
OK to exit the PAL dialog box, and when you return to the
CCP menu choose DO-IT! to save your changes. If you save
to your hard disk, the changes will become effective
immediately. If you save to the network, you will need to
exit and restart Paradox before the changes will take
effect. Paradox supports one BLOb editor at a time. For
additional information on linking a BLOb editor, refer to
Chapter 15 of the Getting Started Guide.
PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 3/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
4. Question:
2
Can I use a Microsoft Windows, Desqview, or OS/2
BLOb editor as my BLOb editor if I am running Paradox in
that environment?
Answer:
Whatever you define as your BLOb editor must be
capable of running from DOS. Applications written
specifically for these environments generally cannot be
started from DOS alone. Because of this, most Microsoft
Windows, Desqview or OS/2 BLOb editors will not work, even
if you are running Paradox in that environment.
5. Question:
How can I import data into my BLOb field?
Answer:
There are three methods for importing BLObs into
Paradox fields: interactively or with a PAL script or
miniscript. For all methods, it is first necessary to set
up the database that will hold the data by either
designing a new database or modifying an existing database
to contain a BLOb field type. Link in your BLOb editor
through the Custom Configuration Program (see Question 4
of this Technical Information sheet).
There are two options for the next step:
o The exact details of the first option depend in
part on what you've defined as your BLOb editor.
Interactively, go into CoEdit mode, go into
fieldview <Ctrl-F> in the BLOb field, insert the
binary file into the $ZMEMZ$.ZZ file and save the
file as $ZMEMZ$.ZZ in your private directory (if
you save the data to this file in any other
directory, Paradox will not bring it into the
field). Paradox automatically reads this file back
into the BLOb field upon returning to Paradox when
you exit your BLOb editor and will display the word
BLOb in the BLOb field.
PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 4/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
For example, if you are using Quattro Pro as your
BLOb editor, when you invoke fieldview in a BLOb
field, Quattro Pro will display an empty
spreadsheet with the name $ZMEMZ$.ZZ. To insert an
existing binary file (in this case a spreadsheet)
into the file $ZMEMZ$.ZZ, perform the following:
Tools | Combine | Copy | File , type in the name of
an existing spreadsheet that you want to write into
the BLOb field, and then perform a File | Save to
save the file $ZMEMZ$.ZZ in your private directory.
To return to Paradox select File | Exit. The BLOb
field that your cursor is on should now display the
word BLOb.
For some BLOb editors, especially if they only
allow viewing of the BLOb, this method will not
work. If this is the case, you must use the second
method.
o The second method for reading files into Paradox is
the FILEREAD or FILEREAD BINARY (the BINARY option
is strongly recommended for reading data into BLOb
fields). Using the BINARY option suppresses
conversion of carriage return/newline pairs to
newlines and is slightly faster. For example we
could use:
FILEREAD BINARY "BLOb.xxx" TO BLOb
[BLObfield] = BLOb
where BLOb.xxx is your existing binary file that we
want to import, BLOb is the name of the variable we
are assigning it to temporarily, and BLObfield is
the name of field that we are reading the file
into. The maximum size of binary file you can
import is 64 megabytes.
For additional information on the FILEREAD command,
refer to the PAL Reference Guide.
PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 5/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
6. Question:
How much data can I store in a binary field in
Paradox?
Answer:
Each field in each record can hold up to 64 megabytes
worth of data, up to a maximum of 4 gigabytes per table.
7. Question:
I have BLOb data that I want users of my database to
be able to view, but not be able to change. Is it
necessary that I use Edit or CoEdit mode?
Answer:
It is necessary to use Edit or CoEdit mode to use
fieldview <Ctrl-F> to access the data, but it is not
necessary that the program that you've defined as your
BLOb editor be capable of making changes to that data. It
is sufficient to have a program that is only capable of
presenting the BLOb. (The exact implementation of this is
highly dependent on what kind of data you store in your
BLOb field and what programs are available to handle this
type of data).
8. Question:
What other restrictions are there on BLOb fields that
I should keep in mind?
Answer:
While it is possible to store many types of data in
BLOb fields, Paradox only directly supports one BLOb
editor at a time. You can change your BLOb editor at any
time through the Custom Configuration Program.
PRODUCT : Paradox NUMBER : 1189
VERSION : 4.0
OS : DOS
DATE : November 12, 1992 PAGE : 6/6
TITLE : Common Questions & Answers: Paradox 4.0 & BLObs
9. Question:
Can I use BLObs to place pictures on my forms and
reports?
Answer:
BLObs may not be placed on forms or reports. Paradox
is a text based environment, and thus graphics such as
pictures are not compatible with this environment. While
BLOb fields may not be used to place graphics on forms,
BLOb fields can be placed on forms. When you view your
table in form view, the BLOb field will display with the
word 'BLOb' if there is data in that field and will be
blank if the field is empty. The data can then be viewed
by invoking fieldview <Ctrl-F>.
[1] WordPerfect copyright WordPerfect Corp., VPIC copyright Bob
Montgomery
[2] Microsoft Windows copyright Microsoft Corporation, Desqview
copyright Quarterdeck Office Systems, Inc., OS/2 copyright IBM
Corporation.
DISCLAIMER: You have the right to use this technical information
subject to the terms of the No-Nonsense License Statement that
you received with the Borland product to which this information
pertains.