Adding new fields to an existing database

Adding new fields to an existing database



I do it all the time.

1. MvCREATE a new db with the extra field(s)
2. Open the old DB
3. Cycle through the old db using MvWHILE
4. On each record, copy the existing data from the old db into the new
one and initialize the new field any way you want.
5. Reneame the new db to the name of the old one, and that's it.

Scot

Andrew Rosborough wrote:
> I have been working on an application and as I realize new needs, the
> best solution would be to create a new field in one of my xbase3
> databases. Is it possible with out loosing everything in the database
> to add one new field?
>

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Adding new fields to an existing database



I wrote up a quick script. For reference it finally worked like this:

<MvOPEN
NAME="users"
DATABASE="users.dbf"
TYPE="xbase3"
INDEX="users.mvx">
<MvOPEN
NAME="oldusers"
DATABASE="oldusers.dbf"
TYPE="xbase3"
INDEX="oldusers.mvx">

<MvGO NAME="oldusers" ROW="top">
<MvWHILE EXPR="{NOT oldusers.d.eof}">
&[oldusers.d.username];

<MvASSIGN NAME="users.d.username" VALUE="{oldusers.d.username}">
<MvASSIGN NAME="users.d.password" VALUE="{oldusers.d.passworde}">
<MvASSIGN NAME="users.d.email" VALUE="{oldusers.d.email}">
<MvADD NAME="users">
<MvSKIP NAME="oldusers">
</MvWHILE>

<MvCLOSE NAME="oldusers">
<MvCLOSE NAME="users">

--
Andrew Rosborough <[email protected]>

Adding new fields to an existing database



>If you do not need to do it programmatically, you can also change the
>structure quicker in a suitable xBase editor. My favourite one is MS
FoxPro,
>but it is certainly possible with others too.

>Ivo

Oh, yes, you're certainly right. My choice is "Database Desktop" from
Borland... because that happens to be installed with Delphi. :-)

Best,
Mikl=F3s

Adding new fields to an existing database



If you do not need to do it programmatically, you can also change the
structure quicker in a suitable xBase editor. My favourite one is MS =
FoxPro,
but it is certainly possible with others too.

Ivo
http://mivo.truxoft.com=20


-----Original Message-----
From: Jegenye 2001 Bt

> I have been working on an application and as I realize new needs, the
> best solution would be to create a new field in one of my xbase3
> databases. Is it possible with out loosing everything in the database
> to add one new field?

Well, the usual technique is to create a new database file with the
additional field(s) and then
copy over the contents with an MvWHILE loop.
Please have a look at any MM module where the Module_Store_Update =
function
is not trivial.

Best,

Mikl=F3s

Adding new fields to an existing database



> I have been working on an application and as I realize new needs, the
> best solution would be to create a new field in one of my xbase3
> databases. Is it possible with out loosing everything in the database
> to add one new field?

Well, the usual technique is to create a new database file with the
additional field(s) and then
copy over the contents with an MvWHILE loop.
Please have a look at any MM module where the Module_Store_Update functio=
n
is not trivial.

Best,

Mikl=F3s

Mikl=F3s Priszny=E1k
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I have been working on an application and as I realize new needs, the
best solution would be to create a new field in one of my xbase3
databases. Is it possible with out loosing everything in the database
to add one new field?

--
Andrew Rosborough <[email protected]>