學分制數據庫（MyDAC）

Question

我想做一個學分系統。如果有用戶信用「警告：你有信用！數量：[在列中的Jeton值]」，如果沒有用戶信用「警告：你沒有信用！我用MyDAC組件

傑頓：用戶信用列（在數據庫中）

如何做到這一點。？

我試圖讓

MyQuery1.Close; 
MyQuery1.SQL.Text :=' select* from uyeler '+ 
        'where nick=:0 and jeton=:1'; 

MyQuery1.Params[0].AsString:=Edit1.Text; 
MyQuery1.Params[1].AsString:=?must?; 

MyQuery1.open; 

If MyQuery1.RecordCount=0 Then 
    Begin 

    MessageDlg('warning: you have not credit!', mtWarning,[mbOK],0) 

End 
Else 
Begin 

    MessageDlg('warning: you have credit! quantity: (Jeton value in column)', mtWarning,[mbOK],0) 

End; 

Answer 1

如果jeton領域是信用，你可以寫這樣的事情。

MyQuery1.Close; 
MyQuery1.SQL.Text :='select jeton from uyeler where nick=:0'; 
MyQuery1.Params[0].AsString:=Edit1.Text; 
MyQuery1.open; 

If (MyQuery1.IsEmpty) or (MyQuery1.FieldByName('jeton').AsDouble<=0) Then 
    Begin 
    MessageDlg('warning: you have not credit!', mtWarning,[mbOK],0) 
    End 
    Else 
    Begin 
    MessageDlg(Format('warning: you have credit! quantity: (%n)',[MyQuery1.FieldByName('jeton').AsDouble]), mtWarning,[mbOK],0); 
    end;