How to retrieve more than one column using ExecuteScalar?

ExecuteScalar executes the query, and returns the first column of the first row in the result set returned by the query. Additional columns or rows are ignored.

To achecive this you need to use SqlCommand.ExecuteReader Method

ExecuteScalar returns first columns of first row ,so you can use a trick like this

var m = cmd.commandtext =    select str(rodeuser)+','+username+','+password  from 
    (select rodeuser,username,password from customer_db_map)

string[] result=m.ToString().Split(new char[] { ',' });
string rodeuser=result[0];

string username=result[1];

string password=result[2];