In this tutorial, I will teach you how to get a valuemember of a combobox using C# and MySQL database. This method has the capability to get ID of the name of person inside a dropdown selection and it would be displayed inside a listbox . This simple manipulation of data will help you when you are dealing with combobox. Lets begin.
Creating Application

Step 1

Open Microsoft Visual Studio 2015 and create a new windows form application for c#.

Step 2

Do the form just like shown below.

Step 3

Open the code editor by pressing the F7 on your keyboard. In the code editor, add a namespace to access MySQL

libraries

1. 
   
2. using
   
   MySql.Data.MySqlClient
   
   ;
   

Step 4

Create a connection between C# and MySQL database. After that, declare all the classes and a string variable that is needed.

1. 
   
2. MySqlConnection con =
   
   new
   
   MySqlConnection(
   
   "server=localhost;user id=root;password=;database=dbsubjects;sslMode=none"
   
   )
   
   ;
   
3. MySqlCommand cmd;
   
4. MySqlDataAdapter da;
   
5. DataTable dt;
   
6. String
   
   sql;
   

Step 5

Create a method to fill the data in a combobox.

1. 
   
2. private
   
   void
   
   fill_data(
   
   string
   
   sql,ComboBox cbo)
   
3. {
   
4. try
   
5. {
   
6. con.
   
   Open
   
   (
   
   )
   
   ;
   
7. cmd =
   
   new
   
   MySqlCommand(
   
   )
   
   ;
   
8. da =
   
   new
   
   MySqlDataAdapter(
   
   )
   
   ;
   
9. dt =
   
   new
   
   DataTable(
   
   )
   
   ;
   
10. 
    
11. cmd.
    
    Connection
    
    =
    
    con;
    
12. cmd.
    
    CommandText
    
    =
    
    sql;
    
13. 
    
14. da.
    
    SelectCommand
    
    =
    
    cmd;
    
15. da.
    
    Fill
    
    (
    
    dt)
    
    ;
    
16. 
    
17. cbo.
    
    DataSource
    
    =
    
    dt;
    
18. cbo.
    
    DisplayMember
    
    =
    
    "fname"
    
    ;
    
19. cbo.
    
    ValueMember
    
    =
    
    "idno"
    
    ;
    
20. cbo.
    
    Text
    
    =
    
    "Select"
    
    ;
    
21. 
    
22. 
    
23. 
    
24. }
    
    catch
    
    (
    
    Exception ex)
    
25. {
    
26. MessageBox.
    
    Show
    
    (
    
    ex.
    
    ToString
    
    (
    
    )
    
    )
    
    ;
    
27. }
    
28. finally
    
29. {
    
30. con.
    
    Close
    
    (
    
    )
    
    ;
    
31. da.
    
    Dispose
    
    (
    
    )
    
    ;
    
32. }
    
33. }
    
34. 
    

Step 6

Write the following codes to clear the listbox and fill the data in a combobox in the first load of the form.

1. 
   
2. private
   
   void
   
   Form1_Load(
   
   object
   
   sender, EventArgs e)
   
3. {
   
4. sql =
   
   "SELECT * FROM `tblstudent`"
   
   ;
   
5. fill_data(
   
   sql, comboBox1)
   
   ;
   
6. listBox1.
   
   Items
   
   .
   
   Clear
   
   (
   
   )
   
   ;
   
7. }
   

Step 7

Double click a combobox and add the following codes to add and display a valuemember of a combobox inside the listbox.

1. 
   
2. private
   
   void
   
   comboBox1_SelectedIndexChanged(
   
   object
   
   sender, EventArgs e)
   
3. {
   
4. listBox1.
   
   Items
   
   .
   
   Clear
   
   (
   
   )
   
   ;
   
5. listBox1.
   
   Items
   
   .
   
   Add
   
   (
   
   comboBox1.
   
   SelectedValue
   
   .
   
   ToString
   
   (
   
   )
   
   )
   
   ;
   
6. }
   

The complete source code is included you can download it and run it on your computer.

For any questions about this article. You can contact me @
Email – [email protected]
Mobile No. – 09305235027 – TNT
Or feel free to comment below.

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