1. The Update 11:48:57 PM 1

2. 2 Types of Updates  1 st type – Update a specific product – covered in previous lecture  2 nd Type – update a range of products – user selects a product type (which may consist of more than one specific product) – and a mass update if performed  The GUI – change the menu so that Update has a sub menu  Also – enable the inline styles option of the menu control so that you change many of the menu control properties 11:48:57 PM 2

3. Modified Menu 11:48:57 PM 3

4. Doing a Mass Update of Data  A Mass update has to be performed by making use of a Dataset and a tableadapter  Add a new Dataset object to your application…as you drag and drop a tableadapter object onto the dataset, the wizard opens up and talks you through the process of configuring the tableadapters for the dataset  It creates a new typed dataset with datatables that you can use to manipulate the web page data 11:48:57 PM 4

5. The Adapter Configuration 11:48:57 PM 5

6. Adding a Parameter 11:48:57 PM 6

7. Choose the Advanced Option of Allowing Updates 11:48:57 PM 7

8. The New Parameterised Product Table DataType/Class  You now have a Typed Dataset available to use in your program 11:48:57 PM 8

9. Scenario  Your want to update the price of a set of products – not just one product e.g. – you want to increase the price of all bread items  First – arrange the GUI so that the product type can be selected and then do a kind’a mass update of the product  This is via a bit of coding where you make use of the typed Dataset 11:48:57 PM 9

10. The GUI  Dropdown box controlled by a Sql Data Source linked to the Product Type Table  Gridview linked to a 2 nd Sql Data Source that is parameterised  …and the effect is … 11:48:57 PM 10

11. The Update part of the GUI 11:48:57 PM 11

12. Now to write the Mass Update Code  Protected Sub btnUpdatePrice_Click(sender As Object, e As System.EventArgs) Handles btnUpdatePrice.Click  Dim DSProd As New DataSetProduct  Dim TAProd As New DataSetProductTableAdapters.ProductTableAdapter  TAProd.Fill(DSProd.Product, DDLProductType.SelectedValue)  For i As Integer = 0 To DSProd.Product.Rows.Count - 1  DSProd.Product.Rows(i).Item("ProductPrice") += txtUpdateAmount.Text  Next  TAProd.Update(DSProd.Product)  GridView1.DataBind()  End Sub 11:48:57 PM 12

13. Update ….cont’d  How about if you wanted to do a specific update?  This can be easily achieved via the datagrid or the detailsview controls  However, if you had to do this manually – it entails manipulation of the SQLDataSource (SQLDS)  A simple demo…You have a movie list table and you wanted to update the quantity on hand  User selects a movie from a webpage…maybe from a dropdown control…you would like to adjust/edit the QOH  You can go for a typed dataset and a Movie table dataAdapter …as was the case in the previous scenario …or you cold do a  …parameterised update via the SQLDS 11:48:57 PM 13

14. A Parameterised Update via the SQLDS  Invoke a SQLDS that retrieves all the Movies …ensure that the SQLDS is allowed to do updates 11:48:57 PM 14

15. A Dropdown List (DDL)  The DDL is convenient to allow selection of the required movie (name)  In order for the DDL to get the movie names from the database, it has to be bound to the SQLDS  The Binding is done so that the DDL displays the Movie name but the actual field selected is the MovieID 11:48:57 PM 15

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17. Enable PostBack and Overwrite  Enable Postback on the DDL and allow the SQLDS to Overwrite update changes that is made to the database 11:48:57 PM 17

18. Now for Configuration of the SQLDS 11:48:57 PM 18  Open up the Update Command from the Properties window of the SQLDS  It has a pre-defined update command that basically scrolls through all records of the Movie Table and checks if any value has changed…if the value has changed…it does an update on the database  However, for the current application, all that we require is that the SQLDS control updates only the QOH for the Movie that we select from the DDL  So the SQL should go something like…  Update tblMovie…set QOH = @QOH…where MovieID=@MovieID

19. SQL and the Wizards  In order to generate a parameterised SQL query – the @ symbol is used  Whenever an @ symbol is used, the wizard opens up a new interface where it asks you for the source of the parameter value  The Parameter window of the SQLDS wizard is sometimes cluttered with unnecessary stuff  You are liberty to clear this up via the Query Builder and then using the Query Builder only to generate the SQL that you require 11:48:57 PM 19

20. The Clutter 11:48:57 PM 20

21. The Cleansing Phase 11:48:57 PM 21

22. The New SQL Update 11:48:57 PM 22

23. Set the Parameter Values 11:48:57 PM 23

24. Sort out the GUI  …and you’re done! 11:48:57 PM 24

25. Extending the Movie App  What if you wanted to hire a movie?...just a primitive hire demo  So – you can select a movie – but now you want to hire the movie as well  Adopting a rather primitive approach – the customer details will simply be recorded – there is no sophistication with regards to customer records  However, once a hire is done – the QOH for the movie needs to be UPDATED  So let’s see what a possible GUI will look like! 11:48:57 PM 25

26. GUI for the Hire  DDL – display movies ( note: movie name is displayed but the value is set to be the Movie ID  The Movie details are displayed by linking the DDL to the Gridview  A new section – DIV is added to enable Movie Hire  The Movie Hire section consists of a label for the date – activated via the PageLoad event handler; 3 textboxes and 2 buttons 11:48:57 PM 26

27. Once the Hire Button is clicked  The customer details and the movie name is recorded in a new table  The big thing is that the QOH needs to be updated to a new value  However, in order to do this the old QOH needs to be retrieved from the Gridview – or you could configure the SQL statement to simply update the QOH by “one less”  However, for this app – we will retrieve the current QOH from the Gridview and use this value to feed the parameter value that is expected for the SQLDS insert command 11:48:57 PM 27

28. The Hire Code  Since the parameter wizard expects a value to come from a control – a hidden label is used to store the value for QOH  Also, the Gridview.Databind is useful since it will provide an immediate updated view of the QOH for the movie list 11:48:57 PM 28

29. The Power of Scope_Identity()  After a new record has been inserted – let’s say a customer record – you wanted to retrieve the ID number of the newly inserted customer  You have to configure the Insert Query of the Sql DataSource so that the Scope_Identity() method is called – this method returns the ID of the newly inserted record 11:48:57 PM 29

30. Configuring the Sql DataSource for Scope_Identity()  On the SQLDs of the Customer Table – modify the Insert Query by adding a semi-colon and the statement Select @CustID = Scope_Identity()  Refresh the Parameter list  Configure the CustID parameter so that  It is output  The data type is Int32 11:48:57 PM 30

31. The GUI and Event Handler  So …once the Register Customer button is clicked…  The Insert method of the Sql Data source is invoked  After the insert has taken place…the SqlDS_Inserted() method is invoked and the value stored in the CustID parameter is returned 11:48:57 PM 31