Alex 3 things firstly > // connection is assigned inside the constructor I'm not abs sure this will work - assignment of the connection may require the component fully functional secondly Are you running this on an MS SQL 7 Server - If so run a trace and find out how far thru the compile SQL process you are getting. Basically the ADOQuery replaces your parameter names with ? and passes it to ADO for compilation (This is how ADO parameters get 'typed') Thirdly Do you have any books on ADO - Programming ADO from M$ press is a must HTH Neven ----- Original Message ----- From: Alex Kouznetsov <[EMAIL PROTECTED]> To: Multiple recipients of list delphi <[EMAIL PROTECTED]> Sent: Wednesday, 27 September 2000 20:40 Subject: [DUG]: Strange database locks with ADO/MSSQL7 > Hi > > >From time to time I encounter strange kind of database locks while using > Delphi/ADO/MSSQL7. > > In one case I found that the reason for the lock was incorrect SQL statement > (something like 'wherecode = ...', ie. missing space). I was getting no > exception, just a table was staying locked until some other DB activity was > in place. > > I had another locking problem while just doing lots of different things with > the same Query. Eg. Set SQL,Open,Close,Set another SQL,ExecSQL,set another > SQL,open,Close etc. This one got misteriously fixed by applying > BeginTransaction and EndTransaction respectively at the beginning and the > end of this chain of Open and ExecSQL statements. > > Latest example is another mistery. > > Here it is (please note, in this example query does not even get open): > > with TMyADOQuery.Create(Nil) do begin > // connection is assigned inside the constructor > SQL.Text := 'select * from mytable where ' + > '((fromdate is NULL) or (fromdate <= :today1))'+ > ' and '+ > '((tilldate is NULL) or (tilldate >= :today2))'; > // deliberately do not do anything else here in this example, > // assigning of the string above to SQL.Text is _enough_ !!! I have > tested. > Free; > end; > > After this I do simple select query from another table which returns no > results, and after that I log that "no result" event into the 3rd table. > That logging (simple insert statement) fails with the timeout. > > To solve the problem I simplify SQL statement to SQL.Text := 'select * from > mytable'. And I have no locking problem !!! > > Sometimes it seems to me that ADO has bugs in parameters area, sometimes it > seems to me that it does not work well when TADOQuery components created in > code and immidiatelly worked with. But these are just my guesses. > > Did anyone experienced anythig like this ? > > Regards > Alex > > > > -------------------------------------------------------------------------- - > New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] > Website: http://www.delphi.org.nz > To UnSub, send email to: [EMAIL PROTECTED] > with body of "unsubscribe delphi" > --------------------------------------------------------------------------- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz To UnSub, send email to: [EMAIL PROTECTED] with body of "unsubscribe delphi"
