C＃从充满SQL选择的数据表中读取值

Question

I am coding win form app, which checks on startup right of the currently logged user. I had these right saved in MS SQL server in the table. When importing data to Datatable, there is no problem. But when I want to read value, there is message "cannot find column xy".

SqlDataAdapter sdaRights = new SqlDataAdapter("SELECT * FROM rights WHERE [user]='" + System.Security.Principal.WindowsIdentity.GetCurrent().Name + "'", conn);

DataTable dtRights = new DataTable(); //this is creating a virtual table  
sdaRights.Fill(dtRights);
Object cellValue = dt.Rows[0][1];
int value = Convert.ToInt32(cellValue);
MessageBox.Show(value.ToString());

I would like, that program would save the value from SQL to int.

Answer 1

You are assuming that you have rows being returned, would be my first guess. You should loop through your DataTable instead of simply trying to access element 0 in it.

DataTable dtRights = new DataTable();
sdaRights.Fill(dtRights);
foreach(DataRow row in dtRights.Rows) {
    Object cellValue = row[1];
    int value = Convert.ToInt32(cellValue);
    MessageBox.Show(value.ToString());
}

Answer 2

        using (SqlConnection con = new SqlConnection("your connection string"))
        {
            using (SqlCommand cmd = new SqlCommand("SELECT [column_you_want] FROM [rights] WHERE [user] = @user"))
            {
                cmd.Parameters.AddWithValue("@user", System.Security.Principal.WindowsIdentity.GetCurrent().Name);
                con.Open();

                int right = Convert.ToInt32(cmd.ExecuteScalar());
            }
        }