dbc vs free table 
Author Message
 dbc vs free table

I'm sort of new to vfox programming, what is the difference or advantage of
dbc vs. free table.

also if I am working with a clients data witch is on dbc.  I notice if I try
to open a single dbf the program asks for the dbc or if you want to free the
dbf. If I free the dbf to work on it stand along what happens when I copy it
back to the original dir and reindex ?

Thanks for any help in advance...

Mike Garcia



Sat, 25 Sep 2004 10:00:50 GMT  
 dbc vs free table

Hi Mike,

Quote:
> I'm sort of new to vfox programming, what is the difference or advantage of
> dbc vs. free table.

Using the DBC gives you some extra things; field names longer than 10 chars,
triggers and rules, ummm, that's as far as I remember.

Quote:
> also if I am working with a clients data witch is on dbc.  I notice if I try
> to open a single dbf the program asks for the dbc or if you want to free the
> dbf. If I free the dbf to work on it stand along what happens when I copy it
> back to the original dir and reindex ?

Nothing, basically.  You'll need to make some effort to get it re-included in
the DBC, because you just freed it.  Inclusion is not on the basis of
location, you have to tell the dbc.

Regards
Mark
-If more of us acted more sensibly,
d'you think Governments might join in?



Sat, 25 Sep 2004 19:51:16 GMT  
 dbc vs free table
Mike,

DBC-based tables have the following features:

    Long field names
    Field captions
    Field default values
    Field formats and input masks
    Table and field comments
    Table and field rules
    Insert, update and delete triggers
    Relational integrity

Long field names and relational integrity each justify using DBC-based
tables over free tables. Together, these features make a compelling argument
for using DBC-based tables in all new VFP applications unless you have a
backward compatiblity requirement.

Disassociate (free) a table from the DBC and you'll lose all its DBC-based
properties because the properties are stored in the DBC file. Re-associating
the table back into the DBC will NOT restore its properties automatically.

The only time I've used a free table is to export data to another
application the only reads DBF files and cannot get the data itself using
ODBC. Those kinds of applications are getting fewer and fewer.

VFP asks you to locate the associated DBC file whenever you move the DBF
file but not the DBC file. Think of the DBC file and all its associated DBF
files as "the database". Keep them together. Also, the data is NOT in the
DBC or "on the dbc". The data is in the DBF files which are associated
(linked) to the DBC file which, in turn, contains information about the DBF
files.

TP


Quote:
> I'm sort of new to vfox programming, what is the difference or advantage
of
> dbc vs. free table.

> also if I am working with a clients data witch is on dbc.  I notice if I
try
> to open a single dbf the program asks for the dbc or if you want to free
the
> dbf. If I free the dbf to work on it stand along what happens when I copy
it
> back to the original dir and reindex ?

> Thanks for any help in advance...

> Mike Garcia



Sat, 25 Sep 2004 22:46:03 GMT  
 dbc vs free table
Add transactions to the list of features supported by DBC-based tables.


Quote:
> Mike,

> DBC-based tables have the following features:

>     Long field names
>     Field captions
>     Field default values
>     Field formats and input masks
>     Table and field comments
>     Table and field rules
>     Insert, update and delete triggers
>     Relational integrity

> Long field names and relational integrity each justify using DBC-based
> tables over free tables. Together, these features make a compelling
argument
> for using DBC-based tables in all new VFP applications unless you have a
> backward compatiblity requirement.

> Disassociate (free) a table from the DBC and you'll lose all its DBC-based
> properties because the properties are stored in the DBC file.
Re-associating
> the table back into the DBC will NOT restore its properties automatically.

> The only time I've used a free table is to export data to another
> application the only reads DBF files and cannot get the data itself using
> ODBC. Those kinds of applications are getting fewer and fewer.

> VFP asks you to locate the associated DBC file whenever you move the DBF
> file but not the DBC file. Think of the DBC file and all its associated
DBF
> files as "the database". Keep them together. Also, the data is NOT in the
> DBC or "on the dbc". The data is in the DBF files which are associated
> (linked) to the DBC file which, in turn, contains information about the
DBF
> files.

> TP



> > I'm sort of new to vfox programming, what is the difference or advantage
> of
> > dbc vs. free table.

> > also if I am working with a clients data witch is on dbc.  I notice if I
> try
> > to open a single dbf the program asks for the dbc or if you want to free
> the
> > dbf. If I free the dbf to work on it stand along what happens when I
copy
> it
> > back to the original dir and reindex ?

> > Thanks for any help in advance...

> > Mike Garcia



Sat, 25 Sep 2004 22:51:36 GMT  
 dbc vs free table

Quote:
> I notice
> if I try to open a single dbf the program asks for the dbc or if you
> want to free the dbf. If I free the dbf to work on it stand along
> what happens when I copy it back to the original dir and reindex ?

When I need to take a table home or otherwise separate it from it's DBC I
create a dummy database and do a COPY TO MyNewTable DATABASE MyNewDatabase.
This creates a new table with the properties of the old one. That way I
don't lose any of the long field names, etc. When I'm done I copy it back
and replace the old one.

--

Cindy Winegarden  MCSD, Microsoft MVP

http://msdn.microsoft.com/vfoxpro  http://foxcentral.net



Sun, 26 Sep 2004 08:54:35 GMT  
 
 [ 5 post ] 

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