Question

I am programmer in asp.net. I am using C#. I have written very lengthy code for query execution in each time. How to re-factor and organize the following code?

MySqlConnection connection = new MySqlConnection(connstring);
string query = "Select fo_region_Name from fo_region where fo_region_DeleteStatus=0";
MySqlCommand command = new MySqlCommand(query, connection);
MySqlDataReader reader;
connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
    ddl_Country.Items.Add(UppercaseFirst(reader[0].ToString()));
}
connection.Close();

query = "Select Fo_Nationality_Name from fo_Nationality a, Fo_region b where a.Fo_Nationality_Type=1 and "
        + "LEFT(a.Fo_Nationality_Code,2)=LEFT(b.fo_region_Name,2)  and  a.Fo_Nationality_DeleteStatus=0 and "
        + "b.fo_region_DeleteStatus=0 Union Select Fo_Nationality_Name from fo_nationality where Fo_Nationality_DeleteStatus=0";
command = new MySqlCommand(query, connection);
connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
    ddl_Nationality.Items.Add(UppercaseFirst(reader[0].ToString()));
}
connection.Close();

query = "select mcs_CreditCard_CardName from mcs_creditcard where mcs_CreditCard_DeleteStatus=0";
command = new MySqlCommand(query, connection);
connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
    ddl_CreditCard.Items.Add(UppercaseFirst(reader[0].ToString()));
}
connection.Close();

Answer 1

Some thoughts:

• Use multiline strings to format your SQL statements.
• There is no need to close and reopen the connection betwween each command execution.
• There is also no need to create new connection and command objects (in this case)
  • If you have parameters on the command objects, it is easier to create new command objects, rather than clearing out the old parameters
• Use var statements to have the C# compiler automatically determine the variable type for you.
• Wrap objects that need to be disposed, in a using block.

---

using (var connection = new MySqlConnection(connstring)) {
    connection.Open();

    using (var command = new MySqlCommand()) {
        MySqlDataReader reader;

        command.CommandText = @"
            SELECT fo_region_Name
            FROM fo_region
            WHERE fo_region_DeleteStatus=0
        ";
        using (reader = command.ExecuteReader()) {
            while (reader.Read()) {
                ddl_Country.Items.Add(UppercaseFirst(reader[0].ToString()));
            }
        }

        command.CommandText = @"
            SELECT Fo_Nationality_Name
            FROM fo_Nationality a,
                Fo_region b
            WHERE a.Fo_Nationality_Type = 1
                AND LEFT(a.Fo_Nationality_Code,2) = LEFT(b.fo_region_Name,2)
                AND b.fo_region_DeleteStatus=0

            UNION SELECT Fo_Nationality_Name 
            FROM fo_nationality
            WHERE Fo_Nationality_DeleteStatus=0
        ";
        using (reader = command.ExecuteReader()) {
            while (reader.Read()) {
                ddl_Nationality.Items.Add(UppercaseFirst(reader[0].ToString()));
            }
        }

        command.CommandText = @"
            SELECT mcs_CreditCard_CardName
            FROM mcs_creditcard
            WHERE mcs_CreditCard_DeleteStatus = 0
        ";
        using (reader = command.ExecuteReader()) {
            while (reader.Read()) {
                ddl_Nationality.Items.Add(UppercaseFirst(reader[0].ToString()));
            }
        }
    }
}

With LINQ (add a using System.Data.Common statement):

        using (reader = command.ExecuteReader()) {
            /*while (reader.Read()) {
                ddl_Country.Items.Add(UppercaseFirst(reader[0].ToString()));
            }*/
            ddl_Country.Items.AddRange((
                from DbDataRecord row in reader
                select new ListItem(
                    UppercaseFirst(reader.GetString(0))
                )
            ).ToArray());
        }