Datareader error while converting string to int

Question

I am getting compile-time error at reader.GetString, any idea why?

Code:

using (var connection = new OleDbConnection())
{
    connection.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Sparrow vivek\Documents\Billing.accdb";
    connection.Open();
    var query = "SELECT ItemCode FROM invoice";
    using (var command = new OleDbCommand(query, connection))
    {
        using (var reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                comboBox1.Items.Add(reader.GetString("ItemCode"));
                comboBox2.Items.Add(reader.GetString("ItemCode"));
            }
        }
    }
}

enter image description here

have you tried comboBox1.Items.Add(reader("ItemCode").toString());? — Harry
– Harry, Commented Dec 15, 2014 at 14:54
the best overloaded method match for system.data.common.DbDataReader.GetString(int) has some invalid arguments — Sparrow vivek
– Sparrow vivek, Commented Dec 15, 2014 at 14:54
"Any idea why?" Yes, you're passing invalid arguments to DbDataReader.GetString(int). Exactly as the error message says! — Lasse V. Karlsen
– Lasse V. Karlsen, Commented Dec 15, 2014 at 14:55

Soner Gönül · Accepted Answer · 2014-12-15 15:08:32Z

4

OleDbDataReader.GetString method takes int as a parameter, not string.

public override string GetString(
    int i
)

It takes the zero-based column number.

Since you get just one column, change it to;

while (reader.Read())
{
    comboBox1.Items.Add(reader.GetString(0));
    comboBox2.Items.Add(reader.GetString(0));
}

edited Dec 15, 2014 at 15:08

answered Dec 15, 2014 at 14:54

Soner Gönül

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1 Comment

grovesNL Over a year ago

This is not SqlDataReader.

grovesNL · Accepted Answer · 2014-12-15 15:01:52Z

2

OleDbDataReader.GetString requires an input of int. It expects the column ordinal, not the column name.

Either use the column ordinal directly, or determine the ordinal ahead of time. You can determine the column ordinal by using OleDbDataReader.GetOrdinal:

comboBox1.Items.Add(reader.GetString(reader.GetOrdinal("ItemCode")));

Since you are doing this in a loop, you could do something like this:

int itemCodeOrdinal = reader.GetOrdinal("ItemCode");
while (reader.Read())
{
    comboBox1.Items.Add(reader.GetString(itemCodeOrdinal));
    comboBox2.Items.Add(reader.GetString(itemCodeOrdinal));
}

edited Dec 15, 2014 at 15:01

answered Dec 15, 2014 at 14:56

grovesNL

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