update-with-dataset.aspx
来自「东软内部材料（四）asp等相关的教学案例 」· ASPX 代码 · 共 163 行
ASPX
163 行
<%@Page Language="C#" debug="true"%>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.OleDb" %>
<%@ Register TagPrefix="wrox" TagName="connect" Src="..\global\connect-strings.ascx" %>
<!DOCTYPE HTML PUBLIC "-// W3C// DTD HTML 4.0 Transitional// EN">
<html><head>
<title>Updating Data with a DataAdapter and DataSet Object</title>
<!-- #include file="..\global\style.inc" -->
</head>
<body bgcolor="#ffffff">
<span class="heading">Updating Data with a DataAdapter and DataSet Object</span><hr />
<!--------------------------------------------------------------------------->
<%// -- insert connection string script --%>
<wrox:connect id="ctlConnectStrings" runat="server"/>
<div>Connection string: <b><span id="outConnect" runat="server"></span></b></div>
<div>SELECT command: <b><span id="outSelect" runat="server"></span></b></div>
<div>INSERT command: <b><span id="outInsert" runat="server"></span></b></div>
<div>DELETE command: <b><span id="outDelete" runat="server"></span></b></div>
<div>UPDATE command: <b><span id="outUpdate" runat="server"></span></b></div>
<div id="outError" runat="server"> </div>
<b>Initial contents of the Books table:</b>
<asp:datagrid id="dgrResult1" runat="server" /><p />
<b>Contents of the Books table after editing:</b>
<asp:datagrid id="dgrResult2" runat="server" /><p />
<b>Note:</b> while this page does execute the Update method of the DataSet, it does not<br />
actually change the original data. It uses a transaction that is rolled back afterwards.</br />
Otherwise, the update would prevent the code from running the next time.
<script language="C#" runat="server">
void Page_Load(Object sender, EventArgs e)
{
// get connection string from ..\global\connect-strings.ascx user control
string strConnect = ctlConnectStrings.OLEDBConnectionString;
outConnect.InnerText = strConnect; // and display it
// specify the SELECT statement to extract the data
string strSelect = "SELECT * FROM BookList WHERE ISBN LIKE '18610022%'";
outSelect.InnerText = strSelect; // and display it
// create a new DataSet object
DataSet objDataSet = new DataSet();
// create a new Connection object using the connection string
OleDbConnection objConnect = new OleDbConnection(strConnect);
// create a new DataAdapter using the connection object and select statement
OleDbDataAdapter objDataAdapter = new OleDbDataAdapter(strSelect, objConnect);
try
{
// fill the dataset with data using the DataAdapter object
objDataAdapter.Fill(objDataSet, "Books");
}
catch (Exception objError)
{
// display error details
outError.InnerHtml = "<b>* Error while accessing data</b>.<br />"
+ objError.Message + "<br />" + objError.Source;
return; // and stop execution
}
// accept the changes to "fix" the current state of the DataSet contents
objDataSet.AcceptChanges();
// declare a variable to reference the Books table
DataTable objTable = objDataSet.Tables["Books"];
// display the contents of the Books table before changing data
dgrResult1.DataSource = objTable.DefaultView;
dgrResult1.DataBind(); // and bind (display) the data
// now change some records in the Books table
objTable.Rows[0].Delete();
objTable.Rows[1]["Title"] = "Amateur Theatricals for Windows 2000";
objTable.Rows[2].Delete();
objTable.Rows[3].Delete();
objTable.Rows[4]["PublicationDate"] = "01-01-2002";
objTable.Rows.RemoveAt(5);
// notice that using the Remove method on row 5 (rather than marking
// it as deleted) means that the next row then becomes row 5
objTable.Rows[5]["ISBN"] = "200000000";
// add a new row using an array of values
Object[] objValsArray = new Object[3];
objValsArray[0] = "200000001";
objValsArray[1] = "Impressionist Guide to Painting Computers";
objValsArray[2] = "05-02-2002";
objTable.Rows.Add(objValsArray);
// display the contents of the Books table after changing the data
dgrResult2.DataSource = objTable.DefaultView;
dgrResult2.DataBind() ; // and bind (display) the data
// declare a variable to hold a Transaction object
OleDbTransaction objTransaction = null;
try
{
// create an auto-generated command builder to create the commands
// to update, insert and delete the data
OleDbCommandBuilder objCommandBuilder = new OleDbCommandBuilder(objDataAdapter);
// set the update, insert and delete commands for the DataAdapter
objDataAdapter.DeleteCommand = objCommandBuilder.GetDeleteCommand();
objDataAdapter.InsertCommand = objCommandBuilder.GetInsertCommand();
objDataAdapter.UpdateCommand = objCommandBuilder.GetUpdateCommand();
// start a transaction so that we can roll back the changes
// must do this on an open Connection object
objConnect.Open();
objTransaction = objConnect.BeginTransaction();
// attach the current transaction to all the Command objects
// must be done after setting Connection property
objDataAdapter.DeleteCommand.Transaction = objTransaction;
objDataAdapter.InsertCommand.Transaction = objTransaction;
objDataAdapter.UpdateCommand.Transaction = objTransaction;
// perform the update on the original data
objDataAdapter.Update(objDataSet, "Books");
}
catch (Exception objError)
{
// rollback the transaction undoing any updates
objTransaction.Rollback();
// display error details
outError.InnerHtml = "<b>* Error while updating original data</b>.<br />"
+ objError.Message + "<br />" + objError.Source;
return; // and stop execution
}
// display the SQL statements that the DataSet used
// these are created automatically when Update is called
outInsert.InnerText = objDataAdapter.InsertCommand.CommandText;
outDelete.InnerText = objDataAdapter.DeleteCommand.CommandText;
outUpdate.InnerText = objDataAdapter.UpdateCommand.CommandText;
// to actually update the source tables just change the next line
// to objTransaction.Commit() or remove the transaction altogether.
// note that you will then have to change the SELECT statement and
// code to be able to run the example again, or rebuild the
// original data from the supplied SQL scripts
objTransaction.Rollback();
}
</script>
<!--------------------------------------------------------------------------->
<!-- #include file="..\global\foot.inc" -->
</body>
</html>
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