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[Execute0426]

Hi guys i have a problem with this code:

 private void comboBox3_SelectedIndexChanged(object sender, EventArgs e)
        {

            listView1.Items.Clear();
            db.Open();
            MySqlCommand SQL1 = new MySqlCommand("Select * From dbbilling.tblcash where `CustomerName` = '" + comboBox3 + "';", db);

            try
            {
                MySqlDataReader dr = SQL1.ExecuteReader();
                while (dr.Read())
                {
                    ListViewItem item = new ListViewItem(dr[0].ToString());
                    item.SubItems.Add(dr[1].ToString());
                    item.SubItems.Add(dr[2].ToString());
                    item.SubItems.Add(dr[3].ToString());
                    item.SubItems.Add(dr[4].ToString());
                    item.SubItems.Add(dr[5].ToString());
                    item.SubItems.Add(dr[6].ToString());
                    item.SubItems.Add(dr[7].ToString());
                    item.SubItems.Add(dr[8].ToString());

                    listView1.Items.Add(item);
                }
                db.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

everytime i click the comboBox, nothings happen.. please help me.

[Mr_KoKa]

You should use

comboBox1.Items[comboBox1.SelectedIndex]

to get current combo box value.

 

Also dr need to be closed after you done with reading data, if you won't close it you won't be able to execute another one.

 

Did you set your ListView type to Details?

You still need to crate columns with

listView1.Columns.Add("ColumnName")

You can loop trough dr.GetName() dr.FieldCount times to build all columns from db columns names.

Also you could loop trough dr values dr.FieldCount - 1 times to build your item.

[dannytech357]

On 10/26/2016 at 6:49 PM, Execute0426 said:

MySqlCommand SQL1 = new MySqlCommand("Select * From dbbilling.tblcash where `CustomerName` = '" + comboBox3 + "';", db);

Please take a little time to learn about SQL injection. It's pretty easy to understand and will save you in the long run. In this case, being a combobox, I could set it to the following

'; Drop table dbbilling.tblcash; --

This would drop the table, with very little effort. Here's what the entire query looks like after everything is plugged in:

MySqlCommand SQL1 = new MySqlCommand("Select * From dbbilling.tblcash where `CustomerName` = ''; Drop table tbbilling.tblcash; --';", db);

In this case, it ends the Select, and begins a drop. Once the drop is complete -- is used as a comment; any further code won't be run. Also, I completely agree with @Mr_KoKa here, though an alternative would be to use

comboBox1.SelectedValue

Another thing: he is closing dr, but it won't always be closed. For instance, if an error occurs, it will remain open. This can be solved by putting the closing call outside the the try, or adding it to inside the catch

[Mr_KoKa]

He is closing connection, but I guess it is closing also reader, is that right?

[fringie]

You should try using LINQ rather than querying the database like that. Easier to read, change, debug and less prone to make mistakes. You can follow this guide to do so (1:40 onwards).