此示例演示了使用 ADO 进行数据库连接。 该示例假设在窗体上放置了一个 DBGrid。

Code

procedure TForm2.FormCreate(Sender: TObject);const  { Connection string }  ConnString =  'Provider=SQLOLEDB.1;Persist Security Info=False;' +  'User ID=%s;Password=%s;Data Source=%s;Use Procedure for Prepare=1;' +  'Auto Translate=True;Packet Size=4096;Use Encryption for Data=False;'+  'Tag with column collation when possible=False';  { SQL Query }  SQLStr = 'SELECT * FROM customer WHERE customer_id = :AnId;';  { User access }  UserName = 'db_user_name';  PassWord = 'db_pass_word';  Server = 'my.db.server';var  ADOConn  : TADOConnection;  ADOQuery : TADOQuery;  DataSrc  : TDataSource;  Param    : TParameter;begin  { Create an ADO connection. }  ADOConn := TADOConnection.Create(Self);  { Set up the provider engine }  { Set up the connection string. }  ADOConn.ConnectionString := Format(ConnString,    [UserName, PassWord, Server]);  { Disable login prompt. }  ADOConn.LoginPrompt := False;  try    ADOConn.Connected := True;  except    on e: EADOError do    begin      MessageDlg('Error while connecting', mtError,                  [mbOK], 0);      Exit;    end;  end;  { Create the query. }  ADOQuery := TADOQuery.Create(Self);  ADOQuery.Connection := ADOConn;  ADOQuery.SQL.Add(SQLStr);  { Update the parameter that was parsed from the SQL query: AnId. }  Param := ADOQuery.Parameters.ParamByName('AnId');  Param.DataType := ftInteger;  Param.Value := 1;  { Set the query to Prepared--it will improve performance. }  ADOQuery.Prepared := true;  try    ADOQuery.Active := True;  except    on e: EADOError do    begin      MessageDlg('Error while doing query', mtError,                  [mbOK], 0);      Exit;    end;  end;  { Create the data source. }  DataSrc := TDataSource.Create(Self);  DataSrc.DataSet := ADOQuery;  DataSrc.Enabled := true;  { Finally, initialize the grid. }  DBGrid1.DataSource := DataSrc;end;

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