I want to fill the first ComboBox with data from another table, fill the second ComboBox with data from another table, and fill the DataGridView with the table that have relationships with both of the other table.

The problem I was talking about.

The relationship that I create

When I tried to do just that, the first ComboBox shows gibberish “System.Data.DataRowView” while the other ComboBox shows an blank and a correct data. The DataGridView on the other hand show rows with a single data in it.

Imports System.Data.OleDb

Public Class RegisterMarkLabTask
    Dim conn As New OleDbConnection
    Dim cmd As OleDbCommand
    Dim dt As New DataTable
    Dim da As New OleDbDataAdapter(cmd)

    Private Sub RegisterMarkLabTask_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        conn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:UsersASUSDocumentsProject2.accdb"
        viewer()
    End Sub

    Private Sub viewer()
        dt.Clear()
        DataGridView1.DataSource = dt
        DataGridView1.DataSource = Nothing

        conn.Open()
        cmd = conn.CreateCommand()
        cmd.CommandType() = CommandType.Text
        da = New OleDbDataAdapter("select * from LabTaskMark", conn)
        da.Fill(dt)
        DataGridView1.DataSource = dt

        da = New OleDbDataAdapter("select StudentMatricNo from Student", conn)
        da.Fill(dt)
        cbLabTaskID.DisplayMember = "StudentMatricNo"
        cbLabTaskID.DataSource = dt

        da = New OleDbDataAdapter("select LabTaskID from LabTask", conn)
        da.Fill(dt)
        cbLabTaskID.DisplayMember = "LabTaskID"
        cbStudentMatricNo.DataSource = dt

        conn.Close()
    End Sub
End Class