ASP.NET Sum of column to string

Question

I'm trying to show the sum of a column as a string. What's wrong? The only output I get from cmd.ExecuteReader(); seems to be: System.Data.OleDb.OleDbDataReader

       protected void TotalHours() {
        DatabaseConnection.Commandstring = ("SELECT SUM ([Time]) FROM tbl_login");
        using (OleDbConnection con = new OleDbConnection(DatabaseConnection.ConString)) {
            try {
                con.Open();
                using (OleDbCommand cmd = new OleDbCommand(DatabaseConnection.Commandstring, con)) {
                    DatabaseConnection.result = cmd.ExecuteReader();
                    txt_TotalTime.Text = ("Total Time: " + DatabaseConnection.result.ToString());
                    con.Close();
                }
            }

            catch (Exception ex) {
                con.Close();
                Debug.WriteLine("Error Selecting Time from Database " + ex.Message);
            }
        }
    }

Habib · Accepted Answer · 2016-04-19 15:43:03Z

1

You don't need ExecuteReader it is usually used to read multiple returned records through a reader. What you need is ExecuteScalar like:

  DatabaseConnection.result = (decimal) cmd.ExecuteScalar();

Remember to cast it to required type. It should be decimal since , it looks like you are doing caculation based on money.

answered Apr 19, 2016 at 15:43

Habib

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2 Comments

BPW Over a year ago

Thank you! That worked! The table in my DB is set to INT, but removing the cast worked fine :) But it will contain money in the future, so you taught me something useful :)

Habib Over a year ago

@BPW, You are welcome, Just to add, with int you can't store decimal points in your table. It would depend on your requirements, but generally for money the data type used should be decimal.

Dmitrii Bychenko · Accepted Answer · 2016-04-19 15:59:51Z

0

If ypu want to use reader you have to read: reader.Read(); do not forget to dispose reader as well (put it into using):

try {
  using (OleDbConnection con = new OleDbConnection(DatabaseConnection.ConString)) {
    con.Open();

    using (OleDbCommand cmd = new OleDbCommand(DatabaseConnection.Commandstring, con)) {
      using (var reader = cmd.ExecuteReader()) {
        if (reader.Read()) // you have to read
          txt_TotalTime.Text = String.Format("Total Time: ", reader.GetValue(0));
      }
    }
  }
}
catch (DbException ex) { // Bad style: do not catch ALL the exceptions
  Debug.WriteLine("Error Selecting Time from Database " + ex.Message);
}

edited Apr 19, 2016 at 15:59

answered Apr 19, 2016 at 15:50

Dmitrii Bychenko

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