InvalidOperationException: Invalid attempt to read when no data is present. (SQL)

Question

      SqlConnection conn = new SqlConnection(AllQuestionsPresented.connectionString);

    SqlCommand cmd = new SqlCommand(sb.ToString(), conn);
    cmd.Parameters.Add("@ThreadsID", SqlDbType.Int).Value = commentIDe;
    cmd.Parameters.Add("@CommentsID", SqlDbType.Int).Value = commentIDe;
    try
    {
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

        if (dr != null && dr["Comments"] != null && dr["Name"] != null && dr["Date"] != null && dr["UserID"]!=null)//> Invalid attempt to read when no data is present.
        {
            Comment = dr["Comments"].ToString();
            UserName = dr["Name"].ToString();
            Reputation=Int32.Parse(dr["Reputation"].ToString());
            Time = (DateTime)AllQuestionsPresented.TryParse(dr["Date"].ToString());
            UserID = (Guid)dr["UserID"];
        }
        dr.Close();
    }
    finally
    {
        if (conn.State != ConnectionState.Closed)
        {
            conn.Close();
        }
    }

Note: I do iterate over that piece of code with while(dr.Read){}... it isnt shown here.

Why do i get that exception and how do i get rid of it

UPDATE:

                 while (reader.Read())//Command runs through all the ThreadIDs that i have!
                {
                    Comments allQ = new Comments((int)reader["CommentsID"]);
                    allComments.Add(allQ);
                }

Comments is the class that the code is in, and it has a method inside the constructor that runs the code that i presented.

It could be that if the loop runs too many times.. Then the exception is being thrown am i right?

How you iterate over the reader seems quite relevant to this error. Could you post a complete code snippet? — Jonas Høgh, Jun 25 '11 at 14:13

score 4 · Accepted Answer · answered Jun 25 '11 at 14:23

4

The following part of your code is illegal

SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

if (dr != null && dr["Comments"] ...)

You have to call the Read method once (and verify that it returns true) before accessing the indexer of the SqlDataReader, as the documentation states:

The default position of the SqlDataReader is before the first record. Therefore, you must call Read to begin accessing any data.

answered Jun 25 '11 at 14:23

Jonas Høgh

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Can i use this: if (dr.HasRows) { – Matrix001 Jun 25 '11 at 15:14

InvalidOperationException: Invalid attempt to read when no data is present. (SQL)

1 Answers1