VB.Net Global DataSets inside a public function - vb.net

Question

I am having some problem with a function that I hope you can help.
My Application is a simple one, it uses an Access database to load employee information and creates letters and financial breakdown sheet from word templates that users can then print and save back to the database.
I started by creating a dataset containing several datatables for each form subroutine but it resulted in literally hundreds of lines of repeated code. But it worked.
What I want to do, is have one dataset containing all the information needed about an employee and be able to reference it over several forms at the same time. So i created a public module that looks like this:
Public Module Datasets
Public update As String
Dim pCn As OleDb.OleDbConnection
Public Function CSofwareDataSet() As DataSet
'open new connection to database
pCn = New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=G:\CGI Project\CorrespondenceSoftware\Database1.accdb; Persist Security Info=False;")
Try
Call pCn.Open() 'opens the connection
Catch ex As Exception
MessageBox.Show("Could not open a database connection! 1")
MessageBox.Show(ex.ToString)
End Try
CSofwareDataSet = New DataSet
Dim daOPG As New OleDb.OleDbDataAdapter("SELECT * FROM Overpayment WHERE PayNumber='" & Main.tbPayNumber.Text & "' AND Gross=1", pCn) 'get all data from Overpayment Details table
Dim daOPN As New OleDb.OleDbDataAdapter("SELECT * FROM Overpayment WHERE PayNumber='" & Main.tbPayNumber.Text & "' AND Net=1", pCn) 'get all data from Overpayment Details table
Dim daOPR As New OleDb.OleDbDataAdapter("SELECT * FROM OvpReasons", pCn) 'get overpayment reasons
Dim daREC As New OleDb.OleDbDataAdapter("SELECT * FROM TaxYear", pCn) 'get recovery date options
Dim daEMP As New OleDb.OleDbDataAdapter("SELECT * FROM EmployeeDetails WHERE PayNumber='" & Main.tbPayNumber.Text & "' AND Active=1 ", pCn) 'get all data from Employee Details table
Dim daCON As New OleDb.OleDbDataAdapter("SELECT * FROM Consultant", pCn) 'get all data from Consultant Details table
Dim daSET As New OleDb.OleDbDataAdapter("SELECT * FROM Settings", pCn) 'get all data from Consultant Details table
'Find the primary key (if missing)
daOPG.MissingSchemaAction = MissingSchemaAction.AddWithKey
daOPN.MissingSchemaAction = MissingSchemaAction.AddWithKey
daOPR.MissingSchemaAction = MissingSchemaAction.AddWithKey
daREC.MissingSchemaAction = MissingSchemaAction.AddWithKey
daEMP.MissingSchemaAction = MissingSchemaAction.AddWithKey
daCON.MissingSchemaAction = MissingSchemaAction.AddWithKey
daSET.MissingSchemaAction = MissingSchemaAction.AddWithKey
'setup prefixes
Dim cbOPG As New OleDb.OleDbCommandBuilder(daOPG)
cbOPG.QuotePrefix = "["
cbOPG.QuoteSuffix = "]"
Dim cbOPN As New OleDb.OleDbCommandBuilder(daOPN)
cbOPG.QuotePrefix = "["
cbOPG.QuoteSuffix = "]"
Dim cbOPR As New OleDb.OleDbCommandBuilder(daOPR)
cbOPG.QuotePrefix = "["
cbOPG.QuoteSuffix = "]"
Dim cbREC As New OleDb.OleDbCommandBuilder(daREC)
cbOPG.QuotePrefix = "["
cbOPG.QuoteSuffix = "]"
Dim cbEMP As New OleDb.OleDbCommandBuilder(daEMP)
cbEMP.QuotePrefix = "["
cbEMP.QuoteSuffix = "]"
Dim cbCON As New OleDb.OleDbCommandBuilder(daCON)
cbEMP.QuotePrefix = "["
cbEMP.QuoteSuffix = "]"
Dim cbSET As New OleDb.OleDbCommandBuilder(daSET)
cbEMP.QuotePrefix = "["
cbEMP.QuoteSuffix = "]"
If CSofwareDataSet.HasChanges Then
Try
daEMP.Update(CSofwareDataSet, "EmployeeDetails")
daOPG.Update(CSofwareDataSet, "OverPaymentGross")
daOPN.Update(CSofwareDataSet, "OverPaymentNet")
daSET.Update(CSofwareDataSet, "Settings")
MessageBox.Show("Success! Records updated.")
update = "0"
Catch ex As Exception
MessageBox.Show("Oops - something went wrong and it didn't update")
update = "0"
End Try
ElseIf CSofwareDataSet.Tables.Count = 0 Then
daOPG.Fill(CSofwareDataSet, "OverPaymentGross")
daOPN.Fill(CSofwareDataSet, "OverPaymentNet")
daOPR.Fill(CSofwareDataSet, "OverPaymentReasons")
daREC.Fill(CSofwareDataSet, "RecoveryDates")
daEMP.Fill(CSofwareDataSet, "EmployeeDetails")
daCON.Fill(CSofwareDataSet, "ConsultantDetails")
daSET.Fill(CSofwareDataSet, "Settings")
End If
'If update = "1" Then
' Try
' daEMP.Update(CSofwareDataSet, "EmployeeDetails")
' daOPG.Update(CSofwareDataSet, "OverPaymentGross")
' daOPN.Update(CSofwareDataSet, "OverPaymentNet")
' daSET.Update(CSofwareDataSet, "Settings")
'
' MessageBox.Show("Success! Records updated.")
' update = "0"
' Catch ex As Exception
' MessageBox.Show("Oops - something went wrong and it didn't update")
' update = "0"
' End Try
' End If
pCn.Close()
End Function
End Module
On each form, it gets referenced like this (as an example):
Imports WeifenLuo.WinFormsUI.Docking
Imports Word = Microsoft.Office.Interop.Word
Imports CorrespondenceSoftware.Datasets
Public Class GrossInput
Dim loading = "1"
Dim NewEmployee = "0" 'sets the default new employee flag to 0
Private pCn As OleDb.OleDbConnection
Private Sub GrossInput_Load(ByVal Sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
Try
If CSofwareDataSet.Tables("EmployeeDetails").Rows.Count > 0 Then
For i As Integer = 0 To CSofwareDataSet.Tables("EmployeeDetails").Rows.Count - 1
cbTitle.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(2)
tbFName.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(3)
tbLName.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(4)
tbAddress1.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(5)
tbAddress2.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(6)
tbAddress3.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(7)
tbAddress4.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(8)
tbPostcode.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(9)
tbWorkLocation.Text = CSofwareDataSet.Tables("EmployeeDetails").Rows(i)(10)
tbWorkLocation.Enabled = False
tbPostcode.Enabled = False
tbAddress4.Enabled = False
tbAddress3.Enabled = False
tbAddress2.Enabled = False
tbAddress1.Enabled = False
tbLName.Enabled = False
tbFName.Enabled = False
cbTitle.Enabled = False
chkMSC.Enabled = False
chkOfficer.Enabled = False
chkStaff.Enabled = False
bnSaveEmp.Enabled = False
bnEditEmp.Enabled = True
Next
End If
If CSofwareDataSet.Tables("EmployeeDetails").Rows(0)(11) = "1" Then
chkOfficer.Checked = True
Else
chkOfficer.Checked = False
End If
If CSofwareDataSet.Tables("EmployeeDetails").Rows(0)(12) = "1" Then
chkStaff.Checked = True
Else
chkStaff.Checked = False
End If
If CSofwareDataSet.Tables("EmployeeDetails").Rows(0)(13) = "1" Then
chkMSC.Checked = True
Else
chkMSC.Checked = False
End If
Catch ex As Exception
MessageBox.Show(ex.ToString)
MessageBox.Show("Employee not found. Ensure pay number is correct and create a new record")
NewEmployee = "1" ' tells the program to create a new record if saved
cbReference.Enabled = False
cbReference.Text = ""
bnEditEmp.Enabled = False
End Try
'display the overpayment references to the user
If CSofwareDataSet.Tables("OverPaymentGross").Rows.Count > 0 Then
For i As Integer = 0 To CSofwareDataSet.Tables("OverPaymentGross").Rows.Count - 1
cbReference.Items.Add(CSofwareDataSet.Tables("OverPaymentGross").Rows(i)(2))
Next
End If
'display the available consultants to the user
If CSofwareDataSet.Tables("ConsultantDetails").Rows.Count > 0 Then
For i As Integer = 0 To CSofwareDataSet.Tables("ConsultantDetails").Rows.Count - 1
cbConsultant.Items.Add(CSofwareDataSet.Tables("ConsultantDetails").Rows(i)(1) & " " & CSofwareDataSet.Tables("ConsultantDetails").Rows(i)(2))
Next
End If
'display the available Overpayment reasons to the user
If CSofwareDataSet.Tables("OverPaymentReasons").Rows.Count > 0 Then
For i As Integer = 0 To CSofwareDataSet.Tables("OverPaymentReasons").Rows.Count - 1
cbReason.Items.Add(CSofwareDataSet.Tables("OverPaymentReasons").Rows(i)(1))
Next
End If
'Load other recovery date options
If CSofwareDataSet.Tables("RecoveryDates").Rows.Count > 0 Then
For i As Integer = 0 To CSofwareDataSet.Tables("RecoveryDates").Rows.Count - 1
cbStartRecovery.Items.Add(CSofwareDataSet.Tables("RecoveryDates").Rows(i)(1))
Next
End If
Catch ex As Exception
MessageBox.Show(ex.ToString) 'Show any errors to the user
End Try
loading = "0"
End Sub
Now! the problem that I'm having is that, this does work and run without any errors BUT every time the CSSoftwareDataSet function runs it populates the tables correctly and returns the expected results but it then deletes the datatable data so every time the function is referenced from a winform it needs to haul all the data from the access database from scratch, severely impacting on the performance of the program. The tables wont update properly because its not storing the datatable information and as soon as its inserted its forgotten but again, produces no errors. An example of my update script looks like this:
Else 'create a new record
'create a new reference
Dim REFRowCount = CSofwareDataSet.Tables("OverPaymentGross").Rows.Count + 1 'count the number of rows in table and add 1
Dim NewREF = "OVPG" & Main.tbPayNumber.Text & "-" & REFRowCount
'Find todays date and reply dates
Dim TodayDatedate = Format(Now.Date(), "dd/MM/yyyy")
Dim ReplyDatedate = Format(Now.Date.AddDays(21), "dd/MM/yyyy")
'Create a new row
Dim OPNew As DataRow = CSofwareDataSet.Tables("OverPaymentGross").NewRow() 'create a variable to contain the new row
OPNew.Item(1) = Main.tbPayNumber.Text
OPNew.Item(2) = NewREF
OPNew.Item(3) = tbOverpaymentAmount.Text.ToString
OPNew.Item(4) = tbMonRec.Text
OPNew.Item(5) = tbTaxP.Text
OPNew.Item(6) = TodayDatedate
OPNew.Item(7) = ReplyDatedate
OPNew.Item(8) = tbMoRep.Text
OPNew.Item(9) = cbStartRecovery.Text
OPNew.Item(10) = "1" 'Set as gross
OPNew.Item(11) = "0" 'do not set as net
OPNew.Item(12) = cbReason.Text
OPNew.Item(13) = tbAI.Text
OPNew.Item(14) = dtpStart.Value.Date
OPNew.Item(15) = dtpFinish.Value.Date
OPNew.Item(16) = cbConsultant.Text
OPNew.Item(17) = tbPosition.Text
Call CSofwareDataSet.Tables("OverPaymentGross").Rows.Add(OPNew) 'fill the new row and insert the data
There must be a solution to this. To create a dataset that holds its data in session while you open other winforms until it is reset. I'm out of ideas because i really don't want to go back to repeating all this code for practically every subroutine in my program.
I hope I've explained it OK .. Any help here will be greatly appreciated.
Many thanks,
Shane

Answer 1

You can declare the DataSet globally, populate it in a function (sub), which is called just at the start, and retrieve the information by accessing the variable rather than by calling the function over and over. Your code uses a somehow ambiguous approach (same name for function and for variable) which, together with the VB rules (functions might not include a Return statement but a variable with the function's name) does not play to your favor.
Sample code converting the DataSet into a public variable and renaming the function (and converting it into a sub: what is the point of a function now?):
Public CSofwareDataSet As DataSet
Public Sub populateDS()
'open new connection to database
pCn = New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=G:\CGI Project\CorrespondenceSoftware\Database1.accdb; Persist Security Info=False;")
Try
Call pCn.Open() 'opens the connection
Catch ex As Exception
MessageBox.Show("Could not open a database connection! 1")
MessageBox.Show(ex.ToString)
End Try
CSofwareDataSet = New DataSet
'Remaining code
End Sub
Call this sub just once (right at the start of your application; or every time new data has to be retrieved from the DB) and continue using CSofwareDataSet as so far (although as a variable, by removing the Call bits; which, on the other hand, are not required in VB.NET at all).