Session 4 From Access Forms to Windows Forms.NET Adam Cogan Database Architect ssw.com.au.

transcript

Session 4Session 4From Access Forms to From Access Forms to Windows Forms .NET Windows Forms .NET

Adam CoganDatabase Architectssw.com.au

ToToFromFrom

OverviewOverview

Access 97 Access 97 toto

Access 2003Access 2003

AccessAccesstoto

SQL ServerSQL Server

AccessAccesstoto

ReportingReportingServicesServices

AccessAccesstoto

WindowsWindowsForms .NETForms .NET

11 22 33 44

AgendaAgenda• Current Problems• What’s New in .NET• Lab: Migrating from Access

Forms to Windows Forms .NET

Breezers Drink Receipt From Outback Oz

AssumptionsAssumptions

• Backend in SQL Server 2000• Using Enterprise Manager for data

management• Access forms front-end• Reports using Reporting Services• Some VBA knowledge

Session Prerequisites (Current Problems)Session Prerequisites (Current Problems)

1. “Our application stopped working on Mary’s machine when we installed the new version of Office”

2. “Our Access database got corrupted and we can’t open it”

3. “Our Access forms run too slowly - we want a small, fast EXE”

4. “Can we stop the continual polling of SQL Server so we can scale this application?”

5. “We want to integrate with other systems”

Enter .NETEnter .NET

• No need for Access runtime or Office for end-user (1)

• Produce an EXE which doesn’t get corrupted like an MDB (2)

• The EXE is small and runs fast (3)• Only explicit updates to database (4)• Web Service Support are built in (use

an open XML-based architecture) (5)

Problems with Bound Access Problems with Bound Access FormsForms

Advantage – Database Connections are Controllable

In Access• Forms perform database queries in the

background• Cannot be controlledIn .NET• Full control over database connections and

queries• Improved performance and scalability

Not as smooth a ride

Problems with Bound Access Problems with Bound Access FormsForms

Advantage – Database Connections are Controllable

In Access

In .NET

Differences In Form DesignDifferences In Form Design

Advantage – A Shallow Learning Curve for Access Developers (1 of 2)

Advantage – A Shallow Learning Curve for Access Developers (2 of 2)

Northwind .NETNorthwind .NET

New Feature – Anchoring Controls

New Feature – Docking Controls

Advantage – Powerful New Controls (1 of 2)

Advantage – Powerful New Controls (2 of 2)

Data FormsData Forms

In Access1. Get Data – Make Queries

Data FormsData Forms

In Access2. Bind – Set the One RecordSource

Data FormsData FormsIn Access

3. Bind – Set the ControlSource for all bound controls

Data FormsData FormsIn .NET

1. Get Data – Create Data Components (DataSets and DataAdapters)

2. Bind – Set the Many Referenced DataSets

3. Bind – Set the DataBindings for all bound controls

Disadvantage – Database Updates Are Not Done Automatically

In Access1. Changes made on forms are

automatically saved

In .NET:1. Add a save button2. Call DataAdapter.Update(DataSet) in

the OnClick event

Differences in Application DesignDifferences in Application Design

Advantage – All .NET Solution Items are Described in Plain Text

In Access• Everything is in the MDB• If damaged, everything stops workingIn .NET• All solution items are in plain text• Forms described in XML• Low chance of corruption• Lightweight

Difference – Data Views

Access Visual Studio .NET

Design Supported

FormCompile and Run Application

Datasheet Not supported

NavigationNavigation

Private Sub previousRecord_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles previousRecord.Click ' Check that the user isn't on the first record. If Not Me._ordersManager.Position = 0 Then _movingRecords = True Me._ordersManager.Position -= 1 _movingRecords = False End If End Sub

Private Sub nextRecord_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles nextRecord.Click ' Check that the user isn't on the last record. If Not Me._ordersManager.Position = Me._ordersManager.Count - 1 Then _movingRecords = True Me._ordersManager.Position += 1 _movingRecords = False End If End Sub

Add / Edit Line ItemsAdd / Edit Line Items

Private Sub editItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles editItem.Click ' Check that there is a row to edit. If Not BindingContext(ordersList, "Orders.OrdersOrder_Details").Position = -1 Then Dim cm As CurrencyManager = CType(BindingContext(ordersList, "Orders.OrdersOrder_Details"), CurrencyManager)

' Get the current row. Dim orderItem As OrdersDataSet.Order_DetailsRow = CType(CType(cm.Current, DataRowView).Row, OrdersDataSet.Order_DetailsRow)

' Pass the current row to the Order Details form. Dim orderDetailsForm As New OrderDetailsPopupForm(orderItem)

' Show the Order Details form and return the result. Dim result As DialogResult = orderDetailsForm.ShowDialog() ' Check if the user clicked "OK".

If result = DialogResult.OK Then CalculateTotals() End If End If End Sub

Save DataSave Data

Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click Me._ordersManager.EndCurrentEdit() ' Check if changes were made If ordersList.HasChanges Then ' Update the Orders table _ordersDA.Adapter.Update(ordersList) ' Update the Order Details table _orderDetailsDA.Adapter.Update(ordersList) End If End Sub

Disadvantage – Multiple Columns Not Supported in Some Controls

• Use .NET ListView instead of Access Listbox• Some programming required for multi-

column ComboBox

Disadvantage – Multiple Columns Not Supported in Some Controls

Disadvantage – The Datasheet View Is Harder to Implement

In Access• View – DatasheetIn .NET:

• Use DataGrid control• Manually bind to database• Hard to implement advanced controls (ComboBox

Disadvantage – Continuous Forms Are Harder to Implement (1 of 4)

In Access• Form Property: Default View = Continuous

Forms In .NET• Not supported in .NET• 2 options

– Tiled user controls– Summary/Detail

• Tiled user controls

• Split into summary/detail for complex subforms

• Split into summary with popup window

Disadvantage – Subforms are Easier to Use than User Controls (1 of 2)

In Access1. Create parent and sub forms2. Add subform/subreport to parent3. Set linkages between parent/subform

Differences In Form DesignDifferences In Form DesignDisadvantage – Subforms are Easier to Use than User Controls (2

of 2)In .NET1. Create Orders form (parent)2. Create user control for Orders Subform form3. Add property to user control to link parent and subform

(code)4. Update the Orders Subform (user control) when the parent

record changes (code)5. Add the Orders Subform (user control) to the Orders form6. Bind the Orders form to the Orders Subform (user control)

Note: We take a different approach with our example (popup window)

Advantage – Form Inheritance1. Add any common form controls and

logic into a base form2. Create new instances of (“inherit”)

the parent form to ensure consistency

3. Make any required changes to logic and controls on child forms

Advantage – Use Windows XP Styles• Easy to implement in .NET

Disadvantage – Read-Only Textboxes are Grayed Out

In Access• Set Locked = YesIn .NET• Set ReadOnly = True• Have to explicitly set the background colour

Disadvantage – Combo Boxes Cannot Be Locked

In Access• Set Locked = YesIn .NET• No automatic way• Capture the SelectedIndexChanged

event and reset the value

Advantage – Applications Are Stored As Binary Executables

In Access• Use compact and repair• Manually compile as MDEIn .NET• Application automatically compiled on

run• Runs efficiently because it is in binary

Advantage – Application Deployment is Easier

In Access:• License for Office Developer Edition

(for runtime), or• Office installed on target machineIn .NET you only need the free .NET

Framework

Advantage – .NET Versions Can Be Run Side-by-Side

In Access:• Upgrading Office can cause issues (as we have

seen)• Can have multiple versions of Office installed –

however MDB associations don’t know enoughIn .NET:• Framework versions can run side-by-side• Apps using 1.0 continue to work alongside 1.1

Advantage – Extending Your Forms to Mobile Devices

?.NET Web Service

Business and Data Access Logic

Difference – Security Model Integrates with Windows

In Access• Maintain two sets of security for forms

(Access) and backend (SQL)

Difference – Security Model Integrates with Windows

In .NET• Use Windows Integrated security• Based on Active Directory – one model

for forms and SQL Server• Check user’s role in code (using

System.Security.Principal namespace)

Disadvantage – No Wizard-Based Security

In Access:• Use the User-level Security Wizard to

automatically set object permissionsIn .NET:• Form permissions must be defined in

Differences in ProgrammingDifferences in Programming

Difference – VBA replaced by VB.NETIn Access you use• VBA• .DLLsIn .NET• VB.NET, C#, J# etc.• Can use components written in other

languages

Differences in ProgrammingDifferences in ProgrammingAdvantage – Improved Language Features• Structured exception handling• Form and code inheritance• XML and XSL functionality for web services• Simple API wrappers – less API calls

– accessing printers– file dialog boxes

• Improved internationalisation and regional customisation

• Create and deploy DLLs, user controls and web services in .NET

Difference – Macros replaced by VB .NETIn Access you use • the visual macro designerIn .NET• you must rewrite as codeTip: Use the Macro to VBA converter to

simplify rewriting

Difference – Responding to Form Events• .NET – new “Handles” keyword• One method can handle multiple

events

• All Access form events can be handled

Private Sub OpenCustomer (…) Handles btnOK.Click, cboCustomers.DoubleClick

End Sub

Advantage – Improved Development Environment (1 of 3)

• Improved Intellisense

• Improved design-time debugging

• Visually build database objects

Advantage – Use Unit Testing Tools to Check Your Code

• Cannot test code in Access• .NET supports testing frameworks eg. nUnit

Difference – Autoexec Macros vs. Startup Forms/Stubs

• In Access:– Startup form– Autoexec Macro

• In .NET:– Select form in project properties– Shared Sub Main()

SummarySummary• Current Problems

– New versions of Office cause applications to stop working

– Corrupt Access databases– Slow, large Access forms– Continual automatic polling of SQL Server,

limiting scalability– Hard to integrate with other systems

• What’s New in .NET• Lab: Migrating Access forms to .NET

For More Information…For More Information…Microsoft Access: Upgrading and Migrating to SQL Server and .NET -

Course Resourceswww.ssw.com.au/ssw/Events/2004AccessToSQLServerAndNET/

Resources.aspxwww.microsoft.com/net

More courses in March – see www.microsoft.com/australia/events/

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Session 4 From Access Forms to Windows Forms.NET Adam Cogan Database Architect ssw.com.au.

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