TextBox1.Text = ComboBox1.Text

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        textbox1.Text = ComboBox1.SelectedItem
End Sub

Public Function GetConnect()
        Dim conn As SqlConnection
        conn = New SqlConnection("server = jery;database = VBtoC#;Trusted_Connection = yes")
        Return conn
End Function
 
 
Private Sub ReadData()
        Dim i As Integer
        Dim cmdStudent As New SqlCommand
        Dim daStudent As New SqlDataAdapter
        Dim dsStudent As New DataSet
        Dim dtStudent As New DataTable
        Dim conn As SqlConnection
 
        conn = GetConnect()
        Try
 
            cmdStudent = conn.CreateCommand
            cmdStudent.CommandText = "SELECT * FROM Student"
            daStudent.SelectCommand = cmdStudent
            daStudent.Fill(dsStudent, "Student") ' Table Name
            dtStudent = dsStudent.Tables("Student") 'Table Name
            For i = 0 To dtStudent.Rows.Count - 1
                cmbNis.Items.Add(dtStudent.Rows(i).Item(0))
            Next
 
        Catch ex As Exception
            MsgBox("Error: " & ex.Source & ": " & ex.Message, MsgBoxStyle.OKOnly, "Connection Error !!")
        End Try
	conn.Close()
End Sub