从访问和列表框中获取数据C＃

Question

i write a program about customer registiriation. customers inf. saved the txt files. and their depts are saved access database. i want to sort depts small to large . i can sorting depts actually but , i wanna sort depts with ıd s of cutomers. how can i do?

private void button2_Click(object sender, EventArgs e)
    {
        //listBox3.Items.Clear();
        OleDbCommand komut = new OleDbCommand();

        conn.Open();


        OleDbCommand cmd = new OleDbCommand(" SELECT RemainingDept FROM Dept_Tbl  ", conn);


        OleDbDataReader dr = cmd.ExecuteReader();

        List<string> liste = new List<string>();


        while ((dr.Read()))
        {

            liste.Add(dr["RemainingDept"].ToString());

        }

        string[] A = liste.ToArray();

        int[] B;
        B = Array.ConvertAll<string, int>(A, int.Parse);

        int tmp;
        for (int i = 0; i <B.Length ; i++)
        {
            for (int j=B.Length-1; j>i; j--)
            {
                if (B[j - 1] > B[j])
                {
                    tmp = B[j - 1];
                    B[j - 1] = B[j];
                    B[j] = tmp;

                }
            }

        }


        listBox3.Items.Clear(); 
        for (int i = 0; i < B.Length; i++)
        {
            listBox3.Items.Add( B[i].ToString());
        }

        conn.Close();
    }
} 

    } 

Example:

My listbox like this code:

30

40

70

I wanna see listbox like:

2 30

1 40

3 70

Answer 1

1. Change your query to SELECT ID, RemainingDept FROM Dept_Tbl ORDER BY RemainingDept DESC .

2. Get rid of the sorting code

3. Change the read line to: liste.Add(dr["ID"] + " " + dr["RemainingDept"]);

Answer 2

1. Class approach:

public class Department
{
    public int ID { get; set; }
    public int RemainingDept { get; set; }
}

private void button2_Click(object sender, EventArgs e)
{

    List<Department> liste = new List<Department>();

    OleDbCommand cmd = new OleDbCommand("SELECT ID, RemainingDept FROM Dept_Tbl ORDER BY RemainingDept", conn);
    OleDbDataReader dr = cmd.ExecuteReader();

    while (dr.Read())
    {
        var dept = new Department()
        {
            ID = Convert.ToInt32(dr["ID"]),
            RemainingDept = Convert.ToInt32(dr["RemainingDept"]);
        };
        liste.Add(dept);
    }

    foreach(var nItem in liste)
    {
        listBox3.Items.Add(nItem.ID + " " + nItem.RemainingDept);
    }
}

---

2. Class-less approach:

Same result with much less code.

private void button2_Click(object sender, EventArgs e)
{
    OleDbCommand cmd = new OleDbCommand("SELECT ID, RemainingDept FROM Dept_Tbl ORDER BY RemainingDept", conn);
    OleDbDataReader dr = cmd.ExecuteReader();

    while (dr.Read())
        listBox3.Items.Add(dr["ID"] + " " + dr["RemainingDept"]);
}

Answer 3

Use this. It'll sort the data and concatenate the two fields together. Convert it to the list, and display. Skip the custom sorting.

OleDbCommand cmd = new OleDbCommand(" SELECT ID || ' ' || RemainingDept FROM Dept_Tbl ORDER BY RemainingDept", conn);