Is this another unsolved mystery? -An error occurred while using adodataset in DLL.

Is this another unsolved mystery? --- Problems with using adodataset in dll: Delphi/Windows SDK/API
Http://www.delphi2007.net/DelphiAPI/html/delphi_20061128102336156.html
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Md. After one day, the headers are too big and the cause is still not found:
In DLL, I declare global ADO: TADODataSet;
DLL load is also available
Coinitialize (NiL );
ADO: = TADODataSet. Create (NiL );
However, when reading a record,
Ado. commandtext: = 'select text from menus where id = '+ inttostr (menuid );
Ado. open;
N: = ADO. recordcount;
Or ADO. recno: = 1;

Master Program When this DLL is called, sometimes the memory address error is reported when it comes to the last two items, but sometimes there is no. there is a mistake. In severe cases, the main program will exit !!!
Use datamoudle. the problem persists !!!
Why ???

You can use sharemem to place it in the first use order of DLL and DLL.

Agree to the upstairs. In addition, if it is not multi-thread, there is no need to add coinitialize (NiL); this sentence may also cause address errors.

Bangding

It's been earlier than sharemem.
Useless.

Coinitialize (NiL) is not used for compilation.

Not so many fans. LZ F1 helps solve all LZ problems ~~

This exception is very strange. Sometimes, even opening the QQ dialog box may also lead to an error!
Or open another software or file, it also causes the error, and all the errors are voiced when accessing the ADO object !!!!
Difficult to solve

In this case, LZ writes ADO: = TADODataSet. Create (NiL); when it is created, it writes it to the exception to capture

ADO: = TADODataSet. Create (NiL );
Try
Execute ADO to read dataCode
Finally
Ado. Free;
And;

Dizzy... please look at the question and answer it again, bro !!
When creating an object, there is no problem at all. Besides, sometimes it works normally?

It may be due to the problem of adoconnection of ADO connection in DLL. If adoconnection is placed in the data module and the data module is also placed in the DLL, this will definitely cause an error. If this is the case, you must explicitly create a data module when loading the DLL.

I made a complete demo for you and tested it for 1000 consecutive times. OK.

Uses
Sysutils,
ActiveX,
ADODB,
Classes;

{$ R *. Res}

Function dataexport: integer;
VaR
Adoconnection: tadoconnection;
Adodataset: TADODataSet;
Begin
Coinitialize (NiL );
Adoconnection: = tadoconnection. Create (NiL );
Adoconnection. connectionstring: = 'provider = sqloledb.1; persist Security info = false; user id = sa; initial catalog = Wangs; Data Source = .';
Adoconnection. loginprompt: = false;
Adodataset: = TADODataSet. Create (NiL );
Adodataset. Connection: = adoconnection;
Try
Adodataset. close;
Adodataset. commandtext: = 'select * From twangs_userinfo ';
Adodataset. open;
Result: = adodataset. recordcount;
Finally
Adodataset. Free;
Adoconnection. Free;
Couninitialize;
End;
End;

Exports
Dataexport;

Begin
End.

Laifeng:
1. Do I have to use adodataset. Connection? Is that the crux of the problem?
2. Can I replace other ADO objects with global ones?

1. Do I have to use adodataset. Connection? Is that the crux of the problem? (Not tested)

2. Can I replace other ADO objects with global ones? Yes (tested)

1. Do I have to use adodataset. Connection? Is that the crux of the problem? Yes (just tested)

The crux of the problem should be

Couninitialize;

However, I suggest you follow the above specifications. All of my systems involve these components. Long-time sandground. Haha

Couninitialize;
I tried it n times, and sometimes an error is reported if I did not add this item.