Cannot open any more tables - OleDbException was unhandled - vb.net

Question

Good Day,
My question is how to handle the exception or get rid of the error pertaining to "Cannot open any more tables". For an overview to the program I was creating, I pull out the record of subject in ms access 2007, I loop to that record to randomly assign a schedule and one by one I insert the newly record with assigned schedule in the table.
My program flow of inserting the record work only for a certain number of times, like almost 200 and at some point it stop and pop-up the oledbexception
Thanks in advance for your time on answering my question.
here is my code for more detailed overview of my program,
Private Sub Assignsched(ByVal rType As String, ByVal subjectCode As String, ByVal SecID As String, ByVal CourseCode As String)
If shrdcon.con.State = ConnectionState.Closed Then
shrdcon.con.Open()
End If
Dim RoomNum As Integer
dtARoom.Clear()
Dim stoploop As Boolean
Dim count As Integer = 0
Dim rm1 As String
RoomAssign = ""
rm1 = "SELECT * FROM tblRoom WHERE RoomType = '" & rType & "'"
Dim dat As New OleDbDataAdapter(rm1, shrdcon.con)
dat.Fill(ds, "ARoom")
stoploop = False
count = 0
Do Until stoploop = "True"
RoomNum = rndm.Next(0, ds.Tables("ARoom").Rows.Count)
RoomAssign = ds.Tables("ARoom").Rows(RoomNum).Item(1)
ScheduleGeneration()
If checkExisting(sTime, eTime, RoomAssign, daypick) = False Then
RoomA = RoomAssign
GenerateOfferingID()
Dim cmd1 As New OleDbCommand()
cmd1.CommandText = "INSERT INTO [tblSubjectOffer]([SubjectOID],[SubjectCode],[SectionID],[Day],[sTime],[eTime],[RoomName],[CourseCode]) VALUES('" & _
myId & "','" & subjectCode & "','" & SecID & "','" & daypick & "'," & sTime & "," & eTime & ",'" & RoomA & "','" & CourseCode & "')"
cmd1.Connection = shrdcon.con
cmd1.ExecuteNonQuery()
cmd1.Dispose()
Dim pipz As New OleDbCommand("Update tblGenerator Set NextNo='" & myId & "' where TableName ='" & "tblSubjectOffer" & "'", shrdcon.con)
pipz.ExecuteNonQuery()
pipz.Dispose()
stoploop = True
Else
stoploop = False
End If
If stoploop = False Then
If count = 30 Then
stoploop = True
Else
count = count + 1
End If
End If
Loop
End Sub

Answer 1

This is typical error happens with Microsoft Jet engine when You have exceeded the maximum number of open TableIDs allowed by the Microsoft Jet database engine, which is 2048 with Jet3.5 engine and 1024 with older engines.
Even though you are closing the Command objects after each use, you are still using the same connection for the whole process, which actually holds the TableID's and is at some point of time exceeding the number of allowed open TableID's.
A probable solution would be to update the Jet Engine with the latest, which is available here
It might solve your problem, but if you are already using the latest engine, you have to look into other options to reduce the number of DB operations.
Try using the UpdateBatch method for applying the updates as a batch.
Hope this helps
Private Sub Command1_Click()
Dim myConnection As ADODB.Connection
Dim rsData As ADODB.Recordset
Set myConnection = New ADODB.Connection
myConnection.ConnectionString = "xxxxxxxxxxxxxxxxxxxx"
myConnection.Open
Set rsData = New ADODB.Recordset
rsData.CursorLocation = adUseClient
rsData.Open "select * from mytable", myConnection, adOpenStatic, adLockBatchOptimistic
For i = 1 To 10000
rsData.AddNew
rsData.Fields(0).Value = 1
rsData.Fields(1).Value = 2
Next i
rsData.UpdateBatch
rsData.Close
myConnection.Close
Set rsData = Nothing
End Sub

Answer 2

Good Evening,
Recently I encounter this type of error and i was able to resolve it by adding
con.close and call conState (a procedure conState- check below) before any insert/update or select statement
In my code i have something like
For i = 0 To DataGridView1.RowCount - 1
reg = DataGridView1.Rows(i).Cells(0).Value
Label2.Text = reg
'i added this two lines
***con.Close()***
***Call conState()***
Dim cmdcheck As New OleDbCommand("Select * from [2015/2016 UG CRF] where regno ='" & reg & "'", con)
Dim drcheck As OleDbDataReader
drcheck = cmdcheck.ExecuteReader
If drcheck.Read = True Then
GoTo A
End If
coursesFirst = String.Empty
coursesSecond = String.Empty
creditFirst = 0
creditSecond = 0
Dim cmdlevel As New OleDbCommand("Select * from [2015/2016 UG registration Biodata 5 april 16] where regno ='" & reg & "'", con)
Dim drlevel As OleDbDataReader
drlevel = cmdlevel.ExecuteReader
If drlevel.Read = True Then
level = drlevel.Item("level").ToString
faculty = drlevel.Item("faculty").ToString
program = drlevel.Item("programme").ToString
End If
...............
next
The conState is a connection testing if connection is closed is should open it again like in below
Public Sub conState()
If con.State = ConnectionState.Closed Then
con.Open()
End If
End Sub
This stop the error message

Answer 3

I got this exception in my C# application and the cause was using OleDbDataReader instances without closing them:
OleDbDataReader reader = cmd.ExecuteReader();
bool result = reader.Read();
reader.Close(); // <= Problem went away after adding this
return result;