The best overloaded method match for 'System.Data.Common.DbDataReader.GetString(int)' has some invalid arguments

Question

I am trying to auto-complete and i get this error and i don't know how to fix it

Here is my code :

void AutoCompleteText(){
        Search_Box.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
        Search_Box.AutoCompleteSource = AutoCompleteSource.CustomSource;
        AutoCompleteStringCollection coll = new AutoCompleteStringCollection();

        SqlCeCommand cmd = new SqlCeCommand("select * from Contact_List   ;", con);
        SqlCeDataReader reader;
        try
        {
            con.Open();
            reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                string sName = reader.GetString("Name");
                coll.Add(sName);
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        Search_Box.AutoCompleteCustomSource = coll;
    }

I get this error from

string sName = reader.GetString("Name");

and I also get : cannot convert from 'String' to 'int'

Need help please

The DataReader `GetString` function wants a column index number, not a column name. You can just use `reader["Name"].ToString()` instead. — LarsTech, Jun 08 '16 at 16:56
It's telling you what the problem is. You need to pass an int, not a string. I suggest reading the documentation. — Heretic Monkey, Jun 08 '16 at 16:59

granadaCoder · Answer 1 · 2016-06-08T19:15:14.170

SqlReader supports the "Get" by using a column name. (SqlReader is not what you have).

IDataReader and DbDataReader "Get" methods need an ORDINAL Number. like 0, 1, 2.

Here is a variation to show what I'm talking about:

   SqlCeCommand cmd = new SqlCeCommand("select MyInt32Column, MyVarCharColumn, MyBitColumn from MyTable;", con);
    SqlCeDataReader reader;
    try
    {
        con.Open();
        reader = cmd.ExecuteReader();
        while (reader.Read())
        {
            int myInt32Value = reader.GetInt32(0);
            string myStringValue = reader.GetString(1);
            bool myBooleanValue = reader.GetBoolean(2);
        }

Bonus: You could also have an issue with the datatype. If so, you can do this:

Use the "GetValue(N)" method.

something like this

object o = reader.GetValue(0);
string mytype = o.GetType().ToString();

this is DEBUGGING code..it will show you the value and the datatype.

then put back the correct .GetString or GetInt32, etc, etc.

PS

This is the danger of using "select *". you should be in the column names. I'll repeat that, you should put in the column names, so you can see which columns you are expecting.

The best overloaded method match for 'System.Data.Common.DbDataReader.GetString(int)' has some invalid arguments

1 Answers1