通過「OleDbDataReader」

Question

我試圖用OleDbDataReader但它返回此錯誤返回錯誤「沒有數據的行列中存在」：

No data exists for the row column 

我使用的是Access數據庫。任何人都可以幫助我找出這個錯誤的根源嗎？這裏是我的代碼：

private void UpdateStudent_Load(object sender, EventArgs e) 
{ 
    OleDbDataAdapter da = new OleDbDataAdapter(); 

    da.SelectCommand = new OleDbCommand(
     "select * from Students where SID= " + U_ID, con); 

    con.Open(); 
    OleDbDataReader rd = da.SelectCommand.ExecuteReader(); 

    if (rd.Read()) 
    { 
     //txtId.Text = U_ID; 
     txtId.Text = rd["SID"].ToString(); 
    } 

    rd.Close(); 
} 

Answer 1

您可以使用此代碼

var queryString = "select * from Students where SID= " + U_ID, con; 
using (OleDbConnection connection = new OleDbConnection(connectionString)) 
{ 
    OleDbCommand command = new OleDbCommand(queryString, connection); 
    connection.Open(); 
    OleDbDataReader reader = command.ExecuteReader(); 

    while (reader.Read()) 
    { 
     txtId.Text = reader["SID"].ToString(); 
    } 
    reader.Close(); 
}