How to use executeReader() method to retrieve the value of just one cell

I need to e开发者_JAVA百科xecute the following command and pass the result to a label. I don't know how can i do it using Reader. Someone can give me a hand?

String sql = "SELECT * FROM learer WHERE learer.id = " + index;
SqlCommand cmd = new SqlCommand(sql,conn);
learerLabel.Text = (String) cmd.ExecuteReader();

As you can see i create the SQL statement and i execute it, but it does not work. Why?

The console says:

Cannot implicitly SqlDataReader to String...

How can i get the desired results as String so the label can display it properly.

using (var conn = new SqlConnection(SomeConnectionString))
using (var cmd = conn.CreateCommand())
{
    conn.Open();
    cmd.CommandText = "SELECT * FROM learer WHERE id = @id";
    cmd.Parameters.AddWithValue("@id", index);
    using (var reader = cmd.ExecuteReader())
    {
        if (reader.Read())
        {
            learerLabel.Text = reader.GetString(reader.GetOrdinal("somecolumn"))
        }
    }
}

It is not recommended to use DataReader and Command.ExecuteReader to get just one value from the database. Instead, you should use Command.ExecuteScalar as following:

String sql = "SELECT ColumnNumber FROM learer WHERE learer.id = " + index;
SqlCommand cmd = new SqlCommand(sql,conn);
learerLabel.Text = (String) cmd.ExecuteScalar();

Here is more information about Connecting to database and managing data.

ExecuteScalar() is what you need here

Duplicate question which basically says use ExecuteScalar() instead.