xbase dinosaur questions 
Author Message
 xbase dinosaur questions

The last time I used FoxPro it was a DOS
application that supported development of
applications and direct database access from a
command prompt.  And I know that FoxPro is very
different now.

But my question is, to what degree can does FoxPro
give legacy support.  Or more specifically, can I
use the current version to type commands from a
prompt using the old xbase language. And does
it provide things like a browse and edit screen
that can be called from a command line.



Tue, 30 Aug 2005 00:59:05 GMT  
 xbase dinosaur questions
Andrew,
It has pretty good backward support including all the specifics you asked about. It's really too bad
you didn't get interested a little earlier - MS had a public beta of VFP 8.0 available from the
beginning of November 2002. Unfortunately the code expired January 31, 2003 and is no longer
available - as in all aspects of life - "Timing is Everything!".

Rick


Quote:
> The last time I used FoxPro it was a DOS
> application that supported development of
> applications and direct database access from a
> command prompt.  And I know that FoxPro is very
> different now.

> But my question is, to what degree can does FoxPro
> give legacy support.  Or more specifically, can I
> use the current version to type commands from a
> prompt using the old xbase language. And does
> it provide things like a browse and edit screen
> that can be called from a command line.



Tue, 30 Aug 2005 04:01:43 GMT  
 xbase dinosaur questions

yes yes yes.

Quote:

>The last time I used FoxPro it was a DOS
>application that supported development of
>applications and direct database access from a
>command prompt.  And I know that FoxPro is very
>different now.

>But my question is, to what degree can does FoxPro
>give legacy support.  Or more specifically, can I
>use the current version to type commands from a
>prompt using the old xbase language. And does
>it provide things like a browse and edit screen
>that can be called from a command line.



Tue, 30 Aug 2005 04:25:49 GMT  
 xbase dinosaur questions
Darn.  That would have been the best way possible
to see if I can work with it.

Hmmm.  Is there a language reference in PDF format
I can download. That would probably cover most of
what I need to know.

Quote:

> Andrew,
> It has pretty good backward support including all the specifics you asked about. It's really too bad
> you didn't get interested a little earlier - MS had a public beta of VFP 8.0 available from the
> beginning of November 2002. Unfortunately the code expired January 31, 2003 and is no longer
> available - as in all aspects of life - "Timing is Everything!".



Tue, 30 Aug 2005 23:41:20 GMT  
 xbase dinosaur questions
Andrew,
No .PDF - it would be huge! The .CHM for 7.0 is 6.0MB+, and 8.0 is 6.2MB+! The whole VFP 7.0 help
file is online at http://msdn.microsoft.com/vfoxpro/techinfo/documentation/default.asp, and it will
likely be switched over to 8.0 soon.

Rick


Quote:
> Darn.  That would have been the best way possible
> to see if I can work with it.

> Hmmm.  Is there a language reference in PDF format
> I can download. That would probably cover most of
> what I need to know.


> > Andrew,
> > It has pretty good backward support including all the specifics you asked about. It's really too
bad
> > you didn't get interested a little earlier - MS had a public beta of VFP 8.0 available from the
> > beginning of November 2002. Unfortunately the code expired January 31, 2003 and is no longer
> > available - as in all aspects of life - "Timing is Everything!".



Wed, 31 Aug 2005 00:16:15 GMT  
 xbase dinosaur questions
Andrew,

Well, I think it handles legacy apps real well.  I am running dbase2,
dbase3, dbase4 and foxbase plus apps using Foxbase 5.0 and 7.0 without any
changes at all, except for font type and size settings, modifying report
layouts (report design is mouse driven to select locations rather than
variable and title length driven), but there is a conversion utility that
works fairly well.  Most of my stuff doesn't need to be sophisticated or
incorporate all the bells and whistles of the latest versions of FoxBase.
You can enter commands from a dot prompt in the command window, browse,
edit, append, use separate indexes, list, display, etc.  All pretty straight
forward.  And, you don't have worry about all the Windows/Microsoft
programming stuff if you don't want to.

Regards, John C. Shepard


Quote:
> The last time I used FoxPro it was a DOS
> application that supported development of
> applications and direct database access from a
> command prompt.  And I know that FoxPro is very
> different now.

> But my question is, to what degree can does FoxPro
> give legacy support.  Or more specifically, can I
> use the current version to type commands from a
> prompt using the old xbase language. And does
> it provide things like a browse and edit screen
> that can be called from a command line.



Wed, 31 Aug 2005 05:13:50 GMT  
 xbase dinosaur questions
Hi John.  Thanks for the additional information.

Quote:
> Well, I think it handles legacy apps real well.  I am running dbase2,
> dbase3, dbase4 and foxbase plus apps using Foxbase 5.0 and 7.0 without any
> changes at all

That does speak for its ability to understand old dBASE commands.
functions, etc.

Quote:
> except for font type and size settings, modifying report
> layouts (report design is mouse driven to select locations rather than
> variable and title length driven), but there is a conversion utility that
> works fairly well.

All my apps are dead and buried.  But this is good to have just in case
I want to haul one out.

Quote:
> use separate indexes

Does it support production index files. The MDX files, along with  
INDEX ON fieldname TAG tagname, and SET ORDER TO.

Quote:
> All pretty straight
> forward.  And, you don't have worry about all the Windows/Microsoft
> programming stuff if you don't want to.

Sounds good.  And now I just thought of another question. Assuming two
related databases but no SET FIELDS TO, can I open browse and edit
windows for both databases and leave them open while I enter commands
from the dot prompt. Then as I enter commands the windows update in
response.  

The way this kind of thing is generally done is to open one window by
typing browse or edit, click in the dot prompt window without first
closing the browse or edit window, type the command to open a window for
the second related database, click the command area again.

Regards, Andrew



Wed, 31 Aug 2005 12:27:58 GMT  
 xbase dinosaur questions
Andrew,

Yep, you can do all that including opening multiple windows, except
production indexes (.MDX) are called compact indexes (.CDX) files.

Regards, John


Quote:
> Hi John.  Thanks for the additional information.

> > Well, I think it handles legacy apps real well.  I am running dbase2,
> > dbase3, dbase4 and foxbase plus apps using Foxbase 5.0 and 7.0 without
any
> > changes at all

> That does speak for its ability to understand old dBASE commands.
> functions, etc.

> > except for font type and size settings, modifying report
> > layouts (report design is mouse driven to select locations rather than
> > variable and title length driven), but there is a conversion utility
that
> > works fairly well.

> All my apps are dead and buried.  But this is good to have just in case
> I want to haul one out.

> > use separate indexes

> Does it support production index files. The MDX files, along with
> INDEX ON fieldname TAG tagname, and SET ORDER TO.

> > All pretty straight
> > forward.  And, you don't have worry about all the Windows/Microsoft
> > programming stuff if you don't want to.

> Sounds good.  And now I just thought of another question. Assuming two
> related databases but no SET FIELDS TO, can I open browse and edit
> windows for both databases and leave them open while I enter commands
> from the dot prompt. Then as I enter commands the windows update in
> response.

> The way this kind of thing is generally done is to open one window by
> typing browse or edit, click in the dot prompt window without first
> closing the browse or edit window, type the command to open a window for
> the second related database, click the command area again.

> Regards, Andrew



Fri, 02 Sep 2005 03:34:50 GMT  
 xbase dinosaur questions
John C. Shepard said

Quote:
> Yep, you can do all that including opening multiple windows, except
> production indexes (.MDX) are called compact indexes (.CDX) files.

FoxPro sure drives a hard bargain, doesn't it. :-)

Hmmm.  I guess that covers what I was afraid of loosing.  Are there any
pluses, like longer field names, more than 254 limit for character
fields.  Anything extra that can be utilized while still doing things
from the prompt with the old xBASE/dBASE commands/functions/etc?



Fri, 02 Sep 2005 14:15:32 GMT  
 xbase dinosaur questions

Quote:

> No .PDF - it would be huge! The .CHM for 7.0 is 6.0MB+, and 8.0 is 6.2MB+! The whole VFP 7.0 help
> file is online at http://msdn.microsoft.com/vfoxpro/techinfo/documentation/default.asp, and it will
> likely be switched over to 8.0 soon.

Thanks, Rick.  I finally had a chance to get over
there and take a look. It's *very* helpful to have
that online. I looked through a lot of the
language reference.

It's a little unclear whether the FIND command can
still be issued. I know to avoid this when writing
code, and use SEEK instead. But it is handy to use
FIND from the dot prompt, mainly because it
doesn't require quotes.



Sun, 04 Sep 2005 01:15:11 GMT  
 xbase dinosaur questions
Instead of FIND, you can use LOCATE / CONTINUE when looking for something that isn't indexed so you
can use a SEEK(). (Note: LOCATE will even use the an index when one exists for the expression being
used!)

Rick

P.S. Even FP 2.0's Help says FIND was included for backward compatibility - it must be a dBase
construct!


Quote:

> > No .PDF - it would be huge! The .CHM for 7.0 is 6.0MB+, and 8.0 is 6.2MB+! The whole VFP 7.0
help
> > file is online at http://msdn.microsoft.com/vfoxpro/techinfo/documentation/default.asp, and it
will
> > likely be switched over to 8.0 soon.

> Thanks, Rick.  I finally had a chance to get over
> there and take a look. It's *very* helpful to have
> that online. I looked through a lot of the
> language reference.

> It's a little unclear whether the FIND command can
> still be issued. I know to avoid this when writing
> code, and use SEEK instead. But it is handy to use
> FIND from the dot prompt, mainly because it
> doesn't require quotes.



Sun, 04 Sep 2005 03:16:35 GMT  
 xbase dinosaur questions
Hi Rick,

Thanks for the reminder about the the other
commands. I'm just sort of fond of using FIND from
the prompt because I don't have to type quotes
around what I'm finding. But no big deal, I could
manage without it.

Quote:
> > P.S. Even FP 2.0's Help says FIND was included for backward compatibility - it must be a dBase
> construct!

Looks like even dBASE might have dropped it. I
just downloaded the language reference for the
current version and FIND is not there. Or maybe
it's undocumented.

Regards,

Andrew



Sun, 04 Sep 2005 08:13:21 GMT  
 xbase dinosaur questions
Hi, guys,

FIND and LOCATE were original dBase commands.  SEEK did not appear until
version 3 of dBase.  LOCATE was used for sequential searches.  SEEK and FIND
was used for random searches (indexed files).  FIND only accepted a literal
character string, either delimited or undelimited.  SEEK accepted any
expression, character, date, or numeric.  I've always used the form FIND
"&memvar" to access a particular record in an indexed database, which still
works, but I think I will start writing code with the SEEK command.

Regards, John C. Shepard



Tue, 06 Sep 2005 15:15:08 GMT  
 xbase dinosaur questions
Andrew,

The following VFP 7.0 information might be helpful:

NAME CREATION:

Data containers and some parameters to commands and functions require a
name. When you create a name in Visual FoxPro, apply the following rules:

Use only letters, underscores, and numbers.
Begin the name with a letter or underscore.
Use 1 to 128 characters, except for field names in free tables and index
tags - those can be 10 characters at most.
Avoid words reserved by Visual FoxPro.
File names follow your operating system's conventions.

VFP 7.0 LIMITS:

Some capacities may be limited by available memory.

Category Feature Number

Table and Index Files

  Maximum # of records per table file 1 billion
  Maximum size of a table file 2 gigabytes
  Maximum # of characters per record 65,500
  Maximum # of fields per record(1) 255
  Maximum # of tables open at one time(2) 255
  Maximum # of characters per table field 254
  Maximum # of bytes per index key in a non-compact index(3) 100
  Maximum # of bytes per index key in a compact index(3) 240
  Maximum # of open index files per table(2) unlimited
  Maximum # of open indexes in all work areas(2) unlimited
  Maximum # of relations unlimited
  Maximum length of relational expressions unlimited

Field Characteristics

  Maximum size of character fields 254
  Maximum size of numeric (and float) fields 20
  Maximum number of characters in field names in a free table 10
  Maximum number of characters in field names in a table contained in a
database 128
  Minimum value of an integer -2,147,483,647
  Maximum value of an integer 2,147,483,647
  Digits of precision in numeric computations
Visual FoxPro can handle numbers up to 9007199254740992 (2^53) in exact
computations. 16
  64 bits = 8 bytes
Largest number = 10 ^ 308    =   2 ^ 1023 -> 10 bits per
   exponent + 1 for exp sign plus 1 for the number's sign => 12 bits.
Leaving 52 bits for the mantissa + 1 for implied normalized bit -> 53 bits
LOG10(2^53) = 15.95 decimal digits accuracy.

Variables and Arrays

  Default # of variables 1,024
  Maximum # of variables 65,000
  Maximum # of arrays 65,000
  Maximum # of elements per array 65,000

Program and Procedure Files

  Maximum # of lines in source program files unlimited
  Maximum size of compiled program
modules(4) 64K
  Maximum # of procedures per file unlimited
  Maximum # of nested DO calls 128
  Maximum # of READ nesting levels 5
  Maximum # of nested structured programming commands  384
  Maximum # of passed parameters 27
  Maximum # of transactions 5

Report Designer Capacities

  Maximum # of objects in a report definition(2) unlimited
  Maximum length of a report definition 20 inches
  Maximum # of grouping levels 128
  Maximum length of character report variables 255

Other Capacities

  Maximum # of open windows (all types)(2) unlimited
  Maximum # of open Browse windows 255
  Maximum # of characters per character string or memory variable 16,777,184
  Maximum # of characters per command line 8,192
  Maximum # of characters per label control on a report 252
  Maximum # of characters per macro substituted line 8,192
  Maximum # of open files  System limit
  Maximum keystrokes in keyboard macro  1,024
  Maximum fields that can be selected by a SQL SELECT statement 255
  Maximum length of a string literal 255

1. If one or more fields allow null values, the limit is reduced by one to
254 fields.
2. Limited by memory and available file handles. .cdx files use only one
file handle.
3. If the collating sequence is set to MACHINE, each character uses one
byte. If the collating sequence is not set to MACHINE, each character uses
two bytes. If the indexed field supports null values, one additional byte is
used in the index key. Note that non-machine indexes are always compact.
4. A program module is one procedure. A program or application can contain
an unlimited number of program modules.



Tue, 06 Sep 2005 15:31:48 GMT  
 xbase dinosaur questions
Thanks John. That's a very helpful list!

BTW, I've been thinking about it more, and I guess
something would not be xbase unless it follows
xbase standards, which would mean 254 limit for
character fields.  I've tended to avoid memo
fields because, for example, I cannot index on a
substring of a memo fields.  But maybe I need to
just give in and get used to using these.



Wed, 07 Sep 2005 02:02:36 GMT  
 
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