Here's some quick and dirty code that works (it probably wants some
exception handling added around the ExecSQL), but hopefully you get the gist
of it, in this example the database DM.IBDBKiwitracker is a TIBDatabase
component on our central Datamodule unit for our application. It assumes the
Database has a default transaction assigned - which the TIBQuery gets in the
absence of a specific one being assigned to it.
l_qry := TIBQuery.Create(nil);
try
l_qry.Database := DM.IBDBKiwitracker;
l_qry.Transaction.StartTransaction;
try
l_qry.SQL.Add('select count(*) from rdb$relations where
Upper(RDB$RELATION_NAME) = (''MYTABLE'') ');
l_qry.Open;
if (l_qry.Fields[0].Asinteger > 0) then
begin
l_qry.Close;
l_qry.SQL.Clear;
l_qry.SQL.Add('drop table MyTable');
l_qry.ExecSQL;
end;
finally
if l_qry.Transaction.InTransaction then
l_qry.Transaction.Commit;
end;
finally
FreeAndNil(l_qry);
end;
You might also want to check out a bit how the RDB$ tables work in
interbase...
From: [email protected] [mailto:[email protected]] On
Behalf Of Jeremy Coulter
Sent: Wednesday, 17 June 2009 9:59 a.m.
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Drop table in Interbase
Thansk for your reply edward. However, I dont normall use Interbase and your
example didnt make a lot of sence. I managed to find a similar example but I
dont follow part of it.
when I run :
select * from rdb$relations WHERE RDB$RELATION_NAME = 'MyTable'
and
DROP TABLE MyTable;
COMMIT;
It tells me DROP is an invalid token. So I assume the "And" is not part of
the SQL statement.
So what I dont follow is, just doing a "SELECT" to see if a record exists
then dropping the table seems like something is missing.
in a programming sense, I would expect something like
IF select * from rdb$relations WHERE RDB$RELATION_NAME = 'MyTable' <> ''
then
DROP TABLE MyTable;
I know thats not real code, but my point is, just because I can do a select,
doesnt tell me if the table exists or not to try to delete it.......I hope
you follow what I am meaning.
Jeremy
On Tue, Jun 16, 2009 at 4:05 PM, John Bird <[email protected]>
wrote:
For a good working example see
http://xkcd.com/327/
(Standard disclaimer - do not try this at home!)
John
----- Original Message -----
From: Jeremy Coulter <mailto:[email protected]>
To: NZ <mailto:[email protected]> Borland Developers Group - Delphi List
Sent: Tuesday, June 16, 2009 3:35 PM
Subject: Re: [DUG] Drop table in Interbase
ok cool I will try that.
Thanks, Jeremy
On Tue, Jun 16, 2009 at 2:54 PM, Edward Koryagin <[email protected]>
wrote:
select * from rdb$relations ...
and
DROP TABLE ....
Edward Koryagin
--- On Tue, 16/6/09, Jeremy Coulter <[email protected]> wrote:
> From: Jeremy Coulter <[email protected]>
> Subject: [DUG] Drop table in Interbase
> To: "NZ Borland Developers Group - Delphi List" <[email protected]>
> Received: Tuesday, 16 June, 2009, 1:31 PM
> Hi all.
> In interbase, how do I drop a table if it already exists?
> I want to check for a table exists and if it does exist,
> drop it.
>
> I have Googled, but I cant seem to find anything. I am
> prob. searching wrong :-)
>
>
> Jeremy
>
>
> -----Inline Attachment Follows-----
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