ASP.NET Tutorial

Editing with a Repeater

A Repeater can be used for database editing, although additional scripting is required beyond that needed for a GridView, DetailsView, or FormView. Also, a Repeater does not incorporate many of the built-in editing features of these other controls. Still, it is not too difficult to adapt this information display control to an editing control as shown in the following example of editing the Books table of the BooksDB.mdb database. What becomes problematic in using a Repeater for editing is the lack of a paging mechanism. This absence limits the Repeater to editing databases of relatively modest sizes.

Note that making actual changes to the BooksDB.mdb database is not permitted in these tutorials; however, all other functions work as expected.

Book Edit

ID	Type	Title	Author	Description	Price	Qty	Sale	Edit


				Get thorough coverage of Oracle Database 10g from the most comprehensive reference available, published by Oracle Press. With in-depth details on all the new features, this powerhouse resource provides an overview of database architecture and Oracle Grid Computing technology, and covers SQL, SQL*Plus, PL/SQL, dynamic PL/SQL, object-oriented features, and Java programming in the Oracle environment. You'll also find valuable database administration and application development techniques, plus an alphabetical reference covering major Oracle commands, keywords, features, and functions, with cross-referencing of topics.
				In Database in Depth, author and well-known database authority Chris Date lays out the fundamentals of the relational model. Don't let a lack to formal education in database theory hold you back. Instead, let Chris's clear explanation of relational concepts, set theory, the difference between model and implementation, relational algebra, normalization, and much more set you apart and well above the competition when it comes to getting work done with a relational database.
				Revised to reflect the needs of today's users, this 10th edition of Database Processing assures that you will learn marketable skills. By presenting SQL SELECT statements near the beginning of the book readers will know early on how to query data and obtain results-seeing firsthand some of the ways that database technology is useful in the marketplace. By utilizing free software downloads, you will be able to actively use a DBMS product by the end of the 2nd chapter. Each topic appears in the context of accomplishing practical tasks. Its spiral approach to database design provides users with enhanced information not available in other database books on the market.
				When using software products with graphical interfaces, we frequently focus so much on the details of how to use the interface that we forget about the general concepts that allow us to understand and use the software effectively. This is particularly true of a powerful database product like Microsoft Access. Novice, and sometimes even experienced, programmers are so concerned with how something is done in Access that they often lose sight of the general principles that underlie their database applications. Access Database Design and Programming takes you behind the details of the Access interface, focusing on the general knowledge necessary for Access power users or developers to create effective database applications.
				Get a developer-focused introduction to the new programmability features in the next version of Microsoft SQL Server-including integration with the Microsoft .NET Framework-and learn powerful new ways to manipulate your servers. Whether you're a developer currently working with T-SQL or Microsoft Visual Studio.NET, or you're responsible for database administration, you'll see how to draw from your existing skills and knowledge to exploit new SQL Server technology. With introductory-level code samples written in both T-SQL and C#, you'll understand how to take advantage of the cross-platform interoperability, native support for XML and Web services, shared language base, and other programming innovations to build better solutions from business intelligence to enterprise data management.
				With this book, you learn by doing, getting your feet wet immediately as you progress through a series of hands-on projects that build on your growing Photoshop knowledge. Simple step-by-step instructions, review questions at the end of each chapter, and a companion CD with all of the book's project files make learning a breeze as the Adobe Creative Team takes you on a self-paced tour of the image-editing powerhouse. This bestselling guide has been completely revised to cover all of Photoshop CS2's new features and creative tools. This comprehensive guide starts with an introductory tour of the software and then progresses on through lessons on everything from Photoshop's interface to more complex topics like color management, Web graphics, and photo retouching.
				In Learning Web Design, author Jennifer Niederst shares the knowledge she's gained from years of web design experience, both as a designer and a teacher. This book starts from the beginning--defining the Internet, the Web, browsers, and URLs--so you don't need to have any previous knowledge about how the Web works. After reading this book, you'll have a solid foundation in HTML, graphics, and design principles that you can immediately put to use in creating effective web pages.
				Offering breakthrough video capabilities and powerful run-time effects, Macromedia Flash Professional 8 is poised to upend the Web video market, posing a serious challenge to Microsoft, RealNetworks, and Apple's efforts in the process. Here to make sure you're ready for it is the official Macromedia training for the program. Through 20-plus hours of project-based instruction, you'll learn how to program for the enhanced Flash Player; use ActionScript to create dynamic interactivity; take advantage of new Flash 8 features like the improved script editor, revamped library interface, and new Undo feature; and more. Simple step-by-step instructions peppered with plenty of visual aids and a CD that includes lesson files and a trial version of Flash Professional 8 leave you with a solid understanding of Flash development and the techniques required to tap your creative potential by producing dynamic, interactive content.
				Michael Freeman has a well-deserved reputation for effectively explaining the concepts behind digital picture-taking to a variety of audiences. Here, he turns his attention to the professionals and advanced hobbyists who are making the move from traditional to digital and want help mastering the technology and meeting their clients' new requirements. Freeman thoroughly answers the most frequently asked questions about the basics of digital capture, from cameras and computers to storage options, printers, and scanners. Photographers will learn the different file formats and how to save images for print or publishing on the web. They'll explore valuable software tools and basic image processing programs that fix common problems, and see how to improve pictures using an assortment of cropping and filtering techniques.
				Trish and Chris Meyer share their years of real-world production experience in this vital update to the acclaimed Creating Motion Graphics with After Effects series. More than a step-by-step review of the features, you learn how this program integrates into real-world production workflows from award-winning artists who make their living using After Effects. This full-color guide is packed with visual examples, and the enclosed DVD-ROM is loaded with source material and projects that encourage you to practice their techniques.
				How Computers Work, 7th Edition, has been one of the bestselling computer books for the last 10 years. This four-color visual tutorial is a must-have for any computer user, from novice to expert. The rich graphics and intricate details about the inner workings of computers have been admired for years by consumers, instructors, professionals, and readers of all ages. A fresh cover and interior provide the reader with superior usability and it is the most aesthetically-pleasing edition yet!
				Push your PC's performance to the limit. Know the differences between: Pentium II, Pentium MMX, Pentium Pro, and earlier CPU chips and choose the best chip for your needs; understand compatibility and feature sets of processor upgrade sockets, motherboards, and chipsets; use Universal Serial Bus ports and devices to simplify peripheral installation, configuration, and improve performance; squeeze the most performance, life, and reliability out of your hard drives; prevent memory headaches: pick the right speed and type of SIMMs and DIMMs, run more programs at once, and work with bigger files; and integrate hot new hardware including 3D graphics accelerators, fast SDRAM memory, Zoomed Video and CardBus PC Cards for your notebook, and NLX motherboards with support for Single Edge Contact processors and Accelerated Graphics Ports.
				Universal Serial Bus System Architecture, Second Edition, based on the 2.0 version of the Universal Serial Bus specification, provides in-depth coverage and a detailed discussion of USB. It focuses on the USB protocol, signaling environment, and electrical specifications, along with the hardware/software interaction required to configure and access USB devices.
				Designing Embedded Hardware is a book about designing small machines for embedded applications. There are many books on the market dedicated to writing code for particular microprocessors, or that stress the philosophy of embedded system design without providing any practical information. This book steers a middle path, telling you what you need to know to create your own products, and distilling much of the lore of embedded systems design into a single volume. It shows you how to build a complete embedded system, add peripherals, and connect your system to other devices.
				Contemporary Logic Design introduces a wide range of software tools including schematic capture, logic simulation, Boolean minimization, multi-level minimization and state assignment. Links the traditional techniques of logic design (such as Karnaugh maps and breadboard techniques) with real-world design examples. Provides comprehensive, early coverage of programmable logic including ROMs, PALs, and PLAs. Includes a variety of examples, exercises, problems, and case studies that illustrate real design problems and challenge the reader to develop practical solutions using modern design tools.
				This edition is completely up-to-date with The Java 2 Platform Standard Edition (J2SE) 1.5. Now includes topics such as autoboxing, enumerations, enhanced for loops, static import statements, variable-length argument lists, and much more. Presents each new concept in the context of a complete, working program, immediately followed by one or more windows showing the program's input/output dialog. A valuable reference for programmers and anyone interested in learning the Java programming language.
				The original authors of C and the first UNIX system present this concise and powerful guide to ANSI standard C programming. This version, building on Kerninghan and Ritchie's classic The C Programming Language, brings readers up-to-date with the finalized ANSI standard for C while teaching users how to take advantage of noted C features like economy of expression, its full set of operators and more. One reader claimed "Just about every C programmer I respect learned C from this book," while another raved th
				The programming language C# was built with the future of application development in mind. Pursuing that vision, C#'s designers succeeded in creating a safe, simple, component-based, high-performance language that works effectively with Microsoft's .NET Framework. Now the favored language among those programming for the Microsoft platform, C# continues to grow in popularity as more developers discover its strength and flexibility. And, from the start, C# developers have relied on Programming C# both as an introduction to the language and a means of further building their skills. The new fourth edition of Programming C#--the top-selling C# book on the market--has been updated to the C# ISO standard as well as changes to Microsoft's implementation of the language.
				PHP is a simple yet powerful open source scripting language for creating dynamic web content. The millions of web sites powered by PHP are testament to its popularity and ease of use. PHP is used by both programmers, who appreciate its flexibility and speed, and web designers, who value its accessibility and convenience. Programming PHP is an authoritative guide to PHP 4, the latest version of the language, and is filled with the unique knowledge of the creator of PHP, Rasmus Lerdorf. This book explains PHP language syntax and programming techniques in a clear and concise manner, with numerous examples that illustrate both correct usage and common idioms. The book also includes style tips and practical programming advice that will help you become not just a PHP programmer, but a good PHP programmer.
				Visual Basic .NET builds on the legendary simplicity of Visual Basic to add the immense power of true object-oriented programming and Microsoft's .NET Framework. Now, for the first time, one of the language's architects has written a definitive technical reference and tutorial for Visual Basic .NET. Moving far beyond the online documentation, Paul Vick presents the language's complete specification, along with descriptions, reference materials, and code samples direct from the Visual Basic .NET design team.
				By staying current, remaining relevant, and adapting to emerging course needs, this text has continued to define the operating systems course. This Seventh Edition not only presents the latest and most relevant systems, it also digs deeper to uncover those fundamental concepts that have remained constant throughout the evolution of today's operating systems. With this strong conceptual foundation in place, students can more easily understand the details related to specific systems.
				Learning the Unix Operating System is a handy book for someone just starting with Unix or Linux, and it's an ideal primer for Mac and PC users of the Internet who need to know a little about Unix on the systems they visit. The fifth edition is the most effective introduction to Unix in print, covering Internet usage for email, file transfers, web browsing, and many major and minor updates to help the reader navigate the ever-expanding capabilities of the operating system.
				Here's the practical, pocket-sized reference for IT professionals supporting Windows .NET Server. Designed for quick referencing, this portable guide covers all the essentials for performing everyday system-administration tasks. Topics include managing workstations and servers, using Microsoft Active Directory services, creating and administering user and group accounts, managing files and directories, data security and auditing, data back-up and recovery, network administration using TCP/IP, WINS, and DNS, and more.
				Whether you're using Linux for personal software projects, for a small office or home office, to provide services to a small group of colleagues, or to administer a site responsible for millions of email and web connections each day, you need quick access to information on a wide range of tools. This book covers all aspects of administering and making effective use of Linux systems. Among its topics are booting, package management, and revision control. But foremost in Linux in a Nutshell are the utilities and commands that make Linux one of the most powerful and flexible systems available.
				Active Directory represents an enormous advance in network administration. It provides a vast set of powerful tools and technologies for managing a network within a native Windows environment. Mastering Active Directory for Windows Server 2003 is the resource you need to take full advantage of all it has to offer. You get a sound introduction to network directory services, then detailed, practical instruction in the work of implementing Active Directory and using all of its tools. This edition has been completely updated to address features new to Active Directory for Windows Server 2003.
				Ajax in Action helps you implement that thinking--it explains how to distribute the application between the client and the server while retaining the integrity of the system. You will learn how to ensure your app is flexible and maintainable, and how good, structured design can help avoid problems like browser incompatibilities. Along the way it helps you unlearn many old coding habits. Above all, it opens your mind to the many advantages gained by placing much of the processing in the browser. If you are a web developer who has prior experience with web technologies, this book is for you.
				ASP.NET allows web sites to display unique pages for each visitor rather than show the same static HTML pages. The release of ASP.NET 2.0 is a revolutionary leap forward in the area of web application development. It brings with it a wealth of new and exciting built-in functions that reduce the amount of code you'll need to write for even the most common applications. With more than 50 new server controls, the number of classes inside ASP.NET 2.0 has more than doubled, and, in many cases, the changes in this new version are dramatic. This book will alert you to every new feature and capability that ASP.NET 2.0 provides so that you'll be prepared to put these new technologies into action.
				This second edition of Cascading Style Sheets: The Definitive Guide completes the discussion of CSS2, explores CSS2.1, and introduces emerging elements of CSS3. Eric A. Meyer uses his trademark wit and humor to explore properties, tags, attributes, and implementation, as well as real-life issues, such as browser support and design guidelines. This book addresses experienced web authors and scripters, as well as novice authors who may be implementing CSS from scratch. Cascading Style Sheets: The Definitive Guide, Second Edition also includes a new foreword by Molly Holzschlag, a steering committee member for the Web Standards Project.
				There are three main technologies married together to create usable, standards-compliant web designs: XHTML for data structure, Cascading Style Sheets for styling your data, and JavaScript for adding dynamic effects and manipulating structure on the fly using the Document Object Model. This book is about the latter of the three. DOM Scripting: Web Design with JavaScript and the Document Object Model gives you everything you need to start using JavaScript and the Document Object Model to enhance your web pages with client-side dynamic effects. Jermey starts off by giving you a basic crash course in JavaScript and the DOM, then moves on to provide you with several real world examples built up from scratch including dynamic image galleries and dynamic menus, and shows you how to manipulate web page style using the CSS DOM, and create markup on the fly.
				Get an expert, developer-focused introduction to the next big innovation in ASP.NET Web programming. Programming authority Dino Esposito takes you inside ASP.NET 2.0 technology, explaining how its updated, more powerful infrastructure allows you to create rich and dynamic Web applications quickly and with less code. Esposito examines how developer best practices with ASP.NET 1.x and classic ASP helped drive the architectural changes in ASP.NET 2.0, and he offers prerelease insights into its final architecture. With concise concept and feature explanations and more than 70 fully functional examples, this comprehensive introduction gives you everything you need to dig into ASP.NET 2.0 right now.

Figure 9-26. Editing a database with a Repeater.

The Repeater Form

The Repeater displays all records and fields in the Books table within a set of data input areas. The data items can be edited directly in the fields and the "Update" button for that record is clicked to rewrite the information to the database. Also associated with each record is a "Delete" button for removing the record from the database. The top row of the Repeater displays blank input areas and an "Insert" button for entering data and creating a new record. Data validation is not performed in this example.

Two AccessDataSource controls are needed. One populates the Repeater with records from the database. The second supplies book types for the drop-down lists. Code for all controls is shown below.

<asp:AccessDataSource id="BookSource" Runat="Server"
  DataFile="../Databases/BooksDB.mdb"
  SelectCommand = "SELECT * FROM Books ORDER BY BookID"/>

<asp:AccessDataSource id="TypeSource" Runat="Server"
  DataFile="../Databases/BooksDB.mdb"
  SelectCommand = "SELECT DISTINCT BookType FROM Books ORDER BY BookType"/>

<h3>Book Edit</h3>

<asp:Label id="EditMessage" Text="&nbsp;" ForeColor="#FF0000"
Runat="Server"/><br/>

<asp:Repeater id="RepeaterEdit" Runat="Server"
  DataSourceID="BookSource"
  OnItemCommand="Edit_Record">
  
  <HeaderTemplate>
  <table id="RepeaterTable" border="1" style="border-collapse:collapse">
  <tr style="background-color:#E0E0E0">
    <th>ID</th>
    <th>Type</th>
    <th>Title</th>
    <th>Author</th>
    <th>Description</th>
    <th>Price</th>
    <th>Qty</th>
    <th>Sale</th>
    <th>Edit</th>
  </tr>
  <tr>
    <td><asp:TextBox id="BookID" Runat="Server" 
          Font-Size="8pt" Width="45px"/></td>
    <td><asp:DropDownList id="BookType" Runat="Server"
          DataSourceID="TypeSource"
          DataTextField="BookType"
          DataValueField="BookType"
          Font-Size="8pt"/></td>
    <td><asp:TextBox id="BookTitle" Runat="Server" 
          Font-Size="8pt" Width="80px"/></td>
    <td><asp:TextBox id="BookAuthor" Runat="Server" 
          Font-Size="8pt" Width="90px"/></td>
    <td><asp:TextBox id="BookDescription" Runat="Server"
          TextMode="MultiLine" Font-Name="Arial"
          Font-Size="7pt" Width="150" Rows="2"/></td>
    <td><asp:TextBox id="BookPrice" Runat="Server" 
          Font-Size="8pt" Width="50px"
          Style="text-align:right"/></td>
    <td><asp:TextBox id="BookQty" Runat="Server"
          Font-Size="8pt" Width="25px"
          Style="text-align:right"/></td>
    <td><asp:CheckBox id="BookSale" Runat="Server"/></td>
    <td nowrap>
        <asp:Button Text="Insert" CommandName="Insert" Runat="Server"
          Font-Size="7pt" Width="45"/></td>
  </tr>
  <tr>
    <td colspan="9" style="border-bottom:solid 1 black"></td>
  </tr>
  </HeaderTemplate>
          
  <ItemTemplate>
  <tr>
    <td><asp:TextBox id="BookID" ReadOnly="True" Runat="Server"
        Text='<%# Eval("BookID") %>'
        Font-Size="8pt" Width="45px"/></td>
    <td><asp:DropDownList id="BookType" Runat="Server"
          DataSourceID="TypeSource"
          DataTextField="BookType"
          DataValueField="BookType"
          SelectedValue='<%# Eval("BookType") %>'
          Font-Size="8pt"/></td>
    <td><asp:TextBox id="BookTitle" Runat="Server"
          Text='<%# Eval("BookTitle") %>'
          Font-Size="8pt" Width="80px"/></td>
    <td><asp:TextBox id="BookAuthor" Runat="Server"
          Text='<%# Eval("BookAuthor") %>'
          Font-Size="8pt" Width="90px"/></td>
    <td><asp:TextBox id="BookDescription" Runat="Server"
          Text='<%# Eval("BookDescription") %>'
          TextMode="MultiLine" Font-Name="Arial" 
          Font-Size="7pt" Width="150" Rows="2"/></td>
    <td><asp:TextBox id="BookPrice" Runat="Server"
          Text='<%# Eval("BookPrice") %>' 
          Font-Size="8pt" Width="50px"
          Style="text-align:right"/></td>
    <td><asp:TextBox id="BookQty" Runat="Server"
          Text='<%# Eval("BookQty") %>'
          Font-Size="8pt" Width="25px"
          Style="text-align:right"/></td>
    <td><asp:CheckBox id="BookSale" Runat="Server"
          Checked='<%# Eval("BookSale") %>'/></td>
    <td nowrap>
        <asp:Button Text="Update" CommandName="Update" Runat="Server"
          Font-Size="7pt" Width="45"/>
        <asp:Button Text="Delete" CommandName="Delete" Runat="Server"
          Font-Size="7pt" Width="45"/></td>
  </tr>
  </ItemTemplate>
  
  <FooterTemplate>
    </table>
  </FooterTemplate>
             
</asp:Repeater>

Listing 9-50. Code for editing with a Repeater control.

You should note that data binding expressions are in the format <%# Eval("field") %>. The Eval() method is used rather than the Bind() method needed when working with a GridView, DetailsView, and FormView.

Locating Repeater Controls

A Repeater responds to user events such as clicks on its enclosed buttons by including an OnItemCommand event handler. In the current example, this event handler calls subprogram Edit_Record when any of the "Insert," "Update," or "Delete" buttons is clicked. The subprogram called by an OnItemCommand event handler must have the argument RepeaterCommandEventArgs. Also, the buttons must include CommandName properties to identify themselves to the called subprogram.

Rows in a Repeater are indexed. The header row is index -1; other rows are indexed beginning with 0. This row index is passed to the OnItemCommand subprogram through its RepeaterCommandEventArgs argument to identify the row on which a button is clicked and to differentiate among the several rows of controls comprising the Repeater. The row index along with a control's id give a unique identifier to each control. It becomes a matter of using the Repeater's FindControl() method to locate individual controls for editing. The first portion of the Edit_Record subprogram illustrates this process.

Sub Edit_Record (Src As Object, Args As RepeaterCommandEventArgs)

  Dim BookID As TextBox = Args.Item.FindControl("BookID")
  Dim BookType As DropDownList = Args.Item.FindControl("BookType")
  Dim BookTitle As TextBox = Args.Item.FindControl("BookTitle")
  Dim BookAuthor As TextBox = Args.Item.FindControl("BookAuthor")
  Dim BookDescription As TextBox = Args.Item.FindControl("BookDescription")
  Dim BookPrice As TextBox = Args.Item.FindControl("BookPrice")
  Dim BookQty As TextBox = Args.Item.FindControl("BookQty")
  Dim BookSale As CheckBox = Args.Item.FindControl("BookSale")

  ...
End Sub

Listing 9-51. Finding Repeater controls on a clicked row.

The argument passed to the subprogram includes a reference to the row (Item) on which a button is clicked. This reference includes an index for the row (Item.ItemIndex ), and it contains the collection of controls making up the row. These controls are accessed by the row's FindControl() method, supplying the id of the control of interest. For example, the reference Args.Item.FindControl("BookID") in the above example locates the TextBox with the identification "BookID" on whichever row a button is clicked. When this reference is assigned to a variable of the same control type, then the script can access properties associated with that particular control in the Repeater.

Dim BookID As TextBox = Args.Item.FindControl("BookID")

Listing 9-52. Finding a TextBox control on a Repeater row.

The above statement permits use of the reference BookID.Text to access the value contained in the TextBox with id="BookID" on whichever row a command button is clicked. In the preceding script, all controls along the reference row are found and assigned to variables of like types. This makes it easy for the script to refer to all data values appearing along that row of the Repeater and to involve them in database insert, update, and delete operations.

Repeater Editing

The remainder of the Edit_Record subprogram to perform insert, update, and delete operations is shown below.

Sub Edit_Record (Src As Object, Args As RepeaterCommandEventArgs)

  Dim BookID As TextBox = Args.Item.FindControl("BookID")
  Dim BookType As DropDownList = Args.Item.FindControl("BookType")
  Dim BookTitle As TextBox = Args.Item.FindControl("BookTitle")
  Dim BookAuthor As TextBox = Args.Item.FindControl("BookAuthor")
  Dim BookDescription As TextBox = Args.Item.FindControl("BookDescription")
  Dim BookPrice As TextBox = Args.Item.FindControl("BookPrice")
  Dim BookQty As TextBox = Args.Item.FindControl("BookQty")
  Dim BookSale As CheckBox = Args.Item.FindControl("BookSale")
  
  If Args.CommandName = "Update" Then
    
    Dim SQLString As String = "UPDATE Books SET " & _
      "BookType = '"         & BookType.SelectedValue & "', " & _
      "BookTitle = '"        & BookTitle.Text         & "', " & _
      "BookAuthor = '"       & BookAuthor.Text        & "', " & _
      "BookDescription = '"  & BookDescription.Text   & "', " & _
      "BookPrice = '"        & BookPrice.Text         & "', " & _
      "BookQty = '"          & BookQty.Text           & "', " & _
      "BookSale = "          & BookSale.Checked       & " "   & _
      "WHERE BookID = '" & BookID.Text & "'"
    BookSource.UpdateCommand = SQLString
    BookSource.Update()
    EditMessage.Text = "Record " & BookID.Text & " updated"
  
  End If
	
  If Args.CommandName = "Insert" Then
    
    Dim SQLString As String = "INSERT INTO Books " & _
      "(BookID, BookType, BookTitle, BookAuthor, BookDescription, " & _
      "BookPrice, BookQty, BookSale) VALUES (" & _
      "'" & BookID.Text            & "', " & _
      "'" & BookType.SelectedValue & "', " & _
      "'" & BookTitle.Text         & "', " & _
      "'" & BookAuthor.Text        & "', " & _
      "'" & BookDescription.Text   & "', " & _
      "'" & BookPrice.Text         & "', " & _
      "'" & BookQty.Text           & "', " & _
      BookSale.Checked             & ")"
    BookSource.InsertCommand = SQLString
    BookSource.Insert()
    EditMessage.Text = "Record " & BookID.Text & " inserted"
  
  End If
  
  If Args.CommandName = "Delete" Then
    
    Dim SQLString As String = "DELETE FROM Books " _ &
                              "WHERE BookID = '" & BookID.Text & "'"
    BookSource.DeleteCommand = SQLString
    BookSource.Delete()
    EditMessage.Text = "Record " & BookID.Text & " deleted"
    
  End If

End Sub

Listing 9-53. Repeater script to edit records.

The subprogram needs to know which button on the row was clicked in order to perform appropriate processing. Recall that the buttons include CommandNames to identify whether to perform "Insert," "Update," or "Delete" operations. The CommandName of the clicked button is contained in the CommandName argument passed to the subprogram. Therefore, by testing Args.CommandName the subprogram can determine which processing action to take.

If the clicked button has the CommandName of "Insert," then the section of the script to add a new record to the database is performed. This section is repeated below.

Processing involves composing an SQL statement to INSERT a new record into the Books table of the database. The SQL statement is assigned to the InsertCommand property of the AccessDataSource for the Repeater, and its Insert() method is called.

Recall from above that controls along the insert row of the Repeater (along the row containing the insert button that is clicked) have been found and assigned to reference variables. For TextBoxes along the row, their Text properties point to their entered values; for the DropDownList, its SelectedValue property is accessed; for the CheckBox, its Checked property is its value. These row values are concatenated inside fixed text strings to compose an appropriate INSERT statement that is issued through the AccessDataSource. After record insertion, the Repeater is automatically re-bound to the data source to display the added record.

A similar process is followed to update existing records. This portion of the Edit_Records subprogram is repeated below.

If the CommandName of the clicked button is "Update," then an SQL UPDATE statement is composed, inserting data values from controls along the same row as the clicked button. Notice that the BookID (key) field is not updated since it is used to locate the database record to update. In fact, the BookID TextBoxes on the edit rows do not permit changing these numbers. They all have ReadOnly="True" property settings.

After the UPDATE statement is composed, it is assigned to the UpdateCommand property of the AccessDataSource and its Update() method is called. After the record is changed, the Repeater redisplays the changes.

Deleting the record on the row containing the clicked "Delete" button is a matter of composing an SQL DELETE statement that includes the value from the BookID TextBox on that row. This statement is assigned to the DeleteCommand property of the AccessDataSource and its Delete() method is called. The redisplayed Repeater is absent the deleted record.

In this example application no validation is perform on inserted or updated fields. These routines are left out to simplify description of the editing routines. It is a simple matter, however, to insert validation routines inside the appropriate sections of code. The following portion of script for inserting new records is augmented with selected validation tests that have been used in previous examples.