ComboBox and showing from datagrid - mysql

Question

Can someone help me out. I have a combobox where the items are from my database. If I drop down the combobox and select an item, the datagridview must show the firstname,lastname etc. My data type at studentno is varchar, the int does not work too. The data will be get from two different table
2nd is how can I refresh the combobox? Because I need to close then reopen the program before the data that will be insert at combobox.
Private Sub ComboBox6_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox6.SelectedIndexChanged
conn.Open()
query = "select student.studentno,student.firstname,student.middlename,student.lastname,subject.subjcode,subject.subjdesc from student,subject where student.studentno = '" & ComboBox6.SelectedText & "' "
cmd = New MySqlCommand(query, conn)
da.SelectCommand = cmd
ds = New DataSet
da.Fill(ds, "ds_student,subject")
DataGridView1.DataSource = ds
DataGridView1.DataMember = "ds_student,subject"
conn.Close()
End Sub

Answer 1

I had the same problem as you and then i came up with this
Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim conn As New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\Folha de Obra com Tabela Clientes.accdb;Persist Security Info=True")
Dim query As String
Dim cmd As New OleDb.OleDbCommand
Dim da As New OleDb.OleDbDataAdapter
Dim ds As New DataSet
conn.Open()
query = ("select * from Obras where IdCliente = " & ComboBox1.ValueMember)
cmd = New OleDb.OleDbCommand(query, conn)
da.SelectCommand = cmd
da.Fill(ds, "NomeObra")
ComboBox2.DataSource = ds.Tables(0)
ComboBox2.DisplayMember = "NomeObra"
ComboBox2.ValueMember = "IdCliente"
conn.Close()
End Sub
I hope it helps you