Using Isolation Level Serialazable

Question

I use Visual Basic/Windows Forms to create my project
I have my form for amending orders ready.
The flow is:
Get order number
Open connection
sqlcommand to check if order number exists
if not, return
Set isolation level serialazable
Get response to "Delete full order"
If response is "Yes":
trans = connlock.BeginTransaction("Delete_OA")
qry = "delete from ilprod where iorno1 = " & miorno1.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
trans.Commit()
MessageBox.Show("OA " & miorno1.Text & "Deleted")
if response is no:
I display the order details and items.
if an item is selected, get response to "Delete item?"
if response is yes,
trans = connlock.BeginTransaction("Delete_Item")
qry = "delete from ilprod where csno = " & mcsno.Text & " and itno = " & mitno.Text
Dim cmd As SqlCommand
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
miorno1.Text = 0
MessageBox.Show("Item " & miorno1.Text & "/" & mnitno.Text & "Deleted")
trans.Commit()
and continue amendment.
if response is no: proceed to amend item details etc.
Finally, save amendments:
qry = "select opamno from opcsno"
Dim cmd = New SqlCommand(qry, connlock, trans)
new_amno.Text = cmd.ExecuteScalar() + 1
qry = "update opcsno set opamno = opamno + 1"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "update opmain set "
qry = qry & "DORNO= " & "'" & DORNOTextBox.Text & "'"
qry = qry & ",DORDT = " & "'" & CDate(DORDTDateTimePicker.Value) & "'"
qry = qry & ",SIP1FL = " & SIP1FLTextBox.Text
qry = qry & ",SIP2FL = " & SIP2FLTextBox.Text
qry = qry & ",SIP3FL = " & SIP3FLTextBox.Text
qry = qry & ",STAXFL = " & STAXFLCOMBO.SelectedValue
qry = qry & ",DESTFL = " & DESTFLCOMBO.Text
qry = qry & ",MODEFL = " & MODEFLCOMBO.SelectedValue
qry = qry & ",CARRFL = " & CARRFLCOMBO.SelectedValue
qry = qry & ",PACKFL = " & PACKFL.SelectedValue
qry = qry & ",PAYTFL = " & PAYTFLCOMBO.SelectedValue
qry = qry & ",SCDLFL = 4"
qry = qry & ",AMNO = " & new_amno.Text
qry = qry & ",IRDT = " & "'" & CDate(IRDTDateTimePicker.Value) & "'"
qry = qry & " WHERE csno = " & mcsno.Text & ""
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = " delete from opnarr where csno = " & mcsno.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
If vbTrue Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'A',"
qry = qry & "'" & PAYTFLCOMBO.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
If vbTrue Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'D'" & ","
qry = qry & "'" & STAXFLCOMBO.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
If mmcd = "Z998" Or mmcd = "Z999" Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'X'" & ","
qry = qry & "'" & mname.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
For Each row In DataGridView1.Rows
If row.selected Then
qry = "update ilprod set qlty = " & row.cells("qlty").value
qry = qry & ",siz1 = " & row.cells("siz1").value & ",siz2 = " & row.cells("siz2").value & ",siz3 = " & row.cells("siz3").value & ",sppr = " & "'" & row.cells("sppr").value & "'"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "update ilprod set pqty = 0, pmtr = 0 where csno = " & mcsno.Text & " and itno = " & mitno.Text & " and pqty < 0"
' This means that qnty will not be equal to inqty+pqty in such records
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "delete from opscdl " & "where csno = " & mcsno.Text & " and itno = " & mitno.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
For Each scdlrow In DataGridView2.Rows
If scdlrow.cells("csno").value = mcsno.Text And scdlrow.cells("itno").value = mitno.Text And scdlrow.cells("sqnty").value <> 0 Then
qry = "insert into opscdl (csno,itno,sqnty,srmtr,sdate,stype,amno) values (" & scdlrow.cells("csno").value & "," & scdlrow.cells("itno").value & "," & scdlrow.cells("sqnty").value & "," & scdlrow.cells("srmtr").value & "," & "Convert(date,'" & scdlrow.cells("sdate").value & "')" & "," & "'" & scdlrow.cells("stype").value & "'" & "," & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
Next
End If
Next
trans.Commit()
When I run the form, the Order is amended successfully: but I do not think the isolation level is set correctly: as I can access the order from another (new query) connection when the amendment is going on and not yet saved
There are a large number of commands between accesing the records from SQL and the above Save Commands.
Can Can someone guide me?
To repeat: the flow is
SET ISOLATION LEVEL
GET ORDER NUMBER FROM SCREEN
DELETE ORDER?
DELETE ITEM?
AMEND OA AND SAVE AMENDMENTS
I apologise if the above has been unclear.
Mohan
MohanSQL

Answer 1

Hi Mohan,
As the issue is more related to Visual Basic/Windows Forms programming, I would like to recommend you post the question in the
Visual Basic forum or
Windows Forms forum. It is appropriate and more experts will assist you.
Also, you can check the following articles about starting database transactions with the specified isolation level in Visual Basic or other projects.
SqlConnection.BeginTransaction Method (IsolationLevel)
http://msdn.microsoft.com/en-us/library/5ha4240h(v=vs.110).aspx
ADO.NET Transactions and Concurrency in VB.NET
http://www.dotnetheaven.com/article/ado.net-transactions-and-concurrency-in-vb.net
Thanks,
Lydia Zhang