Multiselection in vb.net ListBox - sql

Question

I have a list of student names in a listBox,(studentList)I click on a name in the box and get all the students details up ie name, course, subject etc.The code then gets the details from the database(in my case it's access) then displays it in a datagridview.
The code works fine if I just select one item from one(or all)List Boxes.My question is, can I select more than one item per LitsBox.I know I can use SelectedMode property to allow the highlighting but that wont draw the required data from the database.Here is the code I am using vb.10
`Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim con As New OleDb.OleDbConnection
Dim dbProvider As String
Dim dbSource As String
Dim ds As New DataSet
Dim tables As DataTableCollection = ds.Tables
Dim source1 As New BindingSource()
Dim da As New OleDb.OleDbDataAdapter
dbProvider = "PROVIDER=Microsoft.ACE.OLEDB.12.0;"
dbSource = "Data Source = C:\Documents and Settings\Desktop \studentmarks.accdb"
con.ConnectionString = dbProvider & dbSource
con.Open()
Dim isFirstColumn As Boolean = True
Dim student As String = ""
Dim course As String = ""
Dim grade As String = ""
Dim x As String = studentList.Text
Dim y As String = courseList.Text
Dim z As String = gradeList.Text
Dim defaultSQL As String = "SELECT * FROM studentfile "
If studentList.SelectedIndex > -1 Then
If isFirstColumn Then
student = "WHERE student = '" & x & "' "
Else
student = "AND student = '" & x & "' "
End If
isFirstColumn = False
End If
If courseList.SelectedIndex > -1 Then
If isFirstColumn Then
course = "WHERE course = '" & y & "' "
Else
course = "AND course = '" & y & "' "
End If
isFirstColumn = False
End If
If gradeList.SelectedIndex > -1 Then
If isFirstColumn Then
grade = "WHERE grade = '" & z & "' "
Else
grade = "AND grade = '" & z & "' "
End If
isFirstColumn = False
End If
Dim sql As String = defaultSQL & student & course & grade
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "topclass")
Dim view1 As New DataView(tables(0))
source1.DataSource = view1
DataGridView1.DataSource = view1
DataGridView1.Refresh()
DataGridView1.DataSource = view1
DataGridView1.Refresh()
Dim cnt As Integer
cnt = DataGridView1.Rows.Count
TextBox1.Text = cnt - 1
Dim dayclass As String = TextBox1.Text
TextBox8.Text = dayclass
con.Close()
End Sub`
many thanks
grey

Answer 1

Using the .SelectedItems (and a lot of jiggery with the where clause.... you should be able to use this to EITHER have multi-select of single select accross all three listboxes as well as not selecting anything from any of them too...
The only question I would have would be whether you want all the 'AND's as this would mean if you selected two students, you wouldnt get any results... as no two students are the same right? Unless you selected two 'Dave's in which it would return both. For example!
Might suggest changing some for 'OR's or look at what the end result might be? Either way comment and let us know if need any further help
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim con As New OleDb.OleDbConnection
Dim dbProvider As String
Dim dbSource As String
Dim ds As New DataSet
Dim tables As DataTableCollection = ds.Tables
Dim source1 As New BindingSource()
Dim da As New OleDb.OleDbDataAdapter
dbProvider = "PROVIDER=Microsoft.ACE.OLEDB.12.0;"
dbSource = "Data Source = C:\Documents and Settings\Desktop \studentmarks.accdb"
con.ConnectionString = dbProvider & dbSource
con.Open()
Dim student As String = ""
Dim course As String = ""
Dim grade As String = ""
Dim defaultSQL As String = "SELECT * FROM studentfile "
Dim WhereClause As String = ""
Dim StudentCourseGrade As String
'Students---------------------------------------------
For Each stu In studentList.SelectedItems
StudentCourseGrade = "(student='" & stu & "'"
For Each crs In courselist.SelectedItems
StudentCourseGrade = StudentCourseGrade & " AND course = '" & crs & "'"
For Each grd In gradeList.SelectedItems
StudentCourseGrade = StudentCourseGrade & " AND grade = '" & crs & "'"
Next
Next
StudentCourseGrade = StudentCourseGrade & ")"
If WhereClause.Length = 0 Then
WhereClause = "WHERE " & StudentCourseGrade
Else
WhereClause = " OR " & StudentCourseGrade
End If
Next
'Students---------------------------------------------
Dim SQL As String = defaultSQL & WhereClause
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "topclass")
Dim view1 As New DataView(tables(0))
source1.DataSource = view1
DataGridView1.DataSource = view1
DataGridView1.Refresh()
DataGridView1.DataSource = view1
DataGridView1.Refresh()
Dim cnt As Integer
cnt = DataGridView1.Rows.Count
TextBox1.Text = cnt - 1
Dim dayclass As String = TextBox1.Text
TextBox8.Text = dayclass
con.Close()
End Sub
Hth
Chicken