Creating a dynamic DataTable without knowing what is being returned.

public DataTable executeSQL(string sql)
{
DataTable dt = new DataTable();
sqlcmd = new SqlCommand(sql, new SqlConnection(ConnectionString));
if (sqlcmd.Connection.State != System.Data.ConnectionState.Open)
{
sqlcmd.Connection.Open();
}

SqlDataReader dr = sqlcmd.ExecuteReader();
int fc = dr.FieldCount;

Debug.WriteLine("number of columns : "+fc);

//creating columns in the table
for (int i = 0; i < fc; i++)
{
dt.Columns.Add(dr.GetName(i), dr.GetFieldType(i));
}

//adding rows in the table
while (dr.Read())
{
DataRow drow = dt.NewRow();
for (int i = 0; i < fc; i++)
{
drow[i] = dr.GetValue(i);
}
dt.Rows.Add(drow);
}

sqlcmd.Connection.Close();

return dt;
}