关于通过INI连接数据库的一个问题

Question

我是通过INI连接SQL2000数据库的,以下是代码:(但是运行时,第一次点button1正常,但当第二次点button1的时候,就会报错:打开对象时不允许操作...请问怎么处理呢?是什么原因?初学,谢谢)
procedure TForm1.Button1Click(Sender: TObject);
var
FileName,ServerIP,SQLDBName,SQLUserName,SQLPwd:string;
begin
   FileName:=ExtractFilePath(application.ExeName)+'conf.ini';
          with   TInifile.Create(Filename)   do
          begin
              ServerIP:=ReadString('ServerInfo','ServerIP','');
              SQLDBName:=ReadString('ServerInfo','SQLDBName','');
              SQLUserName:=ReadString('ServerInfo','SQLUserID','');
              SQLPwd:=ReadString('ServerInfo','SQLPwd','');
              Destroy;
          end;
   ADOConnection1.ConnectionString:='Provider=SQLOLEDB.1;Password='+SQLPwd+
          ';Persist Security Info=True;'+'User ID='+SQLUserName+';Initial Catalog='
          +SQLDBName+';Data Source='+ServerIP;
   aa.Close;
   aa.SQL.Clear;
   aa.SQL.Add('select * from T');
   aa.Open;
end;

Answer 1

procedure TForm1.Button1Click(Sender: TObject); 
var 
FileName,ServerIP,SQLDBName,SQLUserName,SQLPwd:string; 
begin 
  FileName:=ExtractFilePath(application.ExeName)+'conf.ini';   with  TInifile.Create(Filename)  do 
  begin 
    ServerIP:=ReadString('ServerInfo','ServerIP',''); 
    SQLDBName:=ReadString('ServerInfo','SQLDBName',''); 
    SQLUserName:=ReadString('ServerInfo','SQLUserID',''); 
    SQLPwd:=ReadString('ServerInfo','SQLPwd',''); 
    Free;
  end; 
  
  ADOConnection1.close;
  ADOConnection1.ConnectionString:='Provider=SQLOLEDB.1;Password='+SQLPwd+ 
          ';Persist Security Info=True;'+'User ID='+SQLUserName+';Initial Catalog=' 
          +SQLDBName+';Data Source='+ServerIP; 
  try
    ADOConnection1.open;  
    aa.Close; 
    aa.connection := ADOConnection1;
    aa.SQL.Clear; 
    aa.SQL.Add('select * from T'); 
    aa.Open; 
  except
    raise;
  end;
end;

Answer 2

另外我想知道,dephi程序的入口在哪里?我想程序一启动就连接ini数据库,就不用每个控件事件都写这些代码

Answer 3

點 project ->View  Resource
begin
  Application.Initialize;
  Application.MainFormOnTaskbar := True;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

Answer 4

ADOConnection1.ConnectionString:='Provider=SQLOLEDB.1;Password='+SQLPwd+ 
          ';Persist Security Info=True;'+'User ID='+SQLUserName+';Initial Catalog=' 
          +SQLDBName+';Data Source='+ServerIP; 
前面加 ADOConnection1.close;

Answer 5

不仅仅是 adoConnection，其它如adoDataset，在修改它的连接属性或CommandText时，都要先关闭对象，这是一个良好的编程习惯。

Answer 6

在你的程序基础上改,
form.onshow:
bgein
  Button1.visible:=false;
  Button1Click;
end;
就可以了.

Answer 7

要先关闭对象ADOConnection1，再打开

Answer 8

或在你主窗口formcreate的时候 设置数据库连接

Answer 9

  在FormCreate里加上
  FileName:=ExtractFilePath(application.ExeName)+'conf.ini';   with  TInifile.Create(Filename)  do 
  begin 
    ServerIP:=ReadString('ServerInfo','ServerIP',''); 
    SQLDBName:=ReadString('ServerInfo','SQLDBName',''); 
    SQLUserName:=ReadString('ServerInfo','SQLUserID',''); 
    SQLPwd:=ReadString('ServerInfo','SQLPwd',''); 
    Free;
  end; 
  
  ADOConnection1.close;
  ADOConnection1.ConnectionString:='Provider=SQLOLEDB.1;Password='+SQLPwd+ 
          ';Persist Security Info=True;'+'User ID='+SQLUserName+';Initial Catalog=' 
          +SQLDBName+';Data Source='+ServerIP;
  在
procedure TForm1.Button1Click(Sender: TObject);
begin
  aa.Close;
  aa.SQL.Clear;
  aa.SQL.Add('select * from T');
  aa.Open;
end;