table-mappings.aspx
来自「Professional ASP.NET source code」· ASPX 代码 · 共 155 行
ASPX
155 行
<%@Page Language="C#"%>
<%@Import Namespace="System.Data" %>
<%@Import Namespace="System.Data.OleDb" %>
<%@Import Namespace="System.Data.Common" %>
<%@ Register TagPrefix="wrox" TagName="connect" Src="..\global\connect-strings.ascx" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head>
<title>Using Default and Specific Table and Column Mappings</title>
<!-- #include file="..\global\style.inc" -->
</head>
<body bgcolor="#ffffff">
<span class="heading">Using Default and Specific Table and Column Mappings</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>Books SELECT command: <b><span id="outSelectBooks" runat="server"></span></b></div>
<div>Authors SELECT command: <b><span id="outSelectAuthors" runat="server"></span></b></div>
<div id="outError" runat="server"> </div>
<b>DataSet.Tables Collection</b>
<asp:datagrid id="dgrTables" runat="server" /><br />
<b>DataSet.Relations Collection</b>
<asp:datagrid id="dgrRelations" runat="server" /><br />
<b>Contents of DataSet.Tables(0)</b>
<asp:datagrid id="dgrBooksData" runat="server" /><br />
<b>Contents of DataSet.Tables(1)</b>
<asp:datagrid id="dgrAuthorsData" runat="server" /><br />
<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 BookList data
string strSelectBooks = "SELECT * FROM BookList WHERE ISBN LIKE '18610033%'";
outSelectBooks.InnerText = strSelectBooks; // and display it
// specify the SELECT statement to extract the BookAuthor data
string strSelectAuthors = "SELECT * FROM BookAuthors WHERE ISBN LIKE '18610033%'";
outSelectAuthors.InnerText = strSelectAuthors ; // and display it
// create a new Connection object using the connection string
OleDbConnection objConnect = new OleDbConnection(strConnect);
// create a new Command object
OleDbCommand objCommand = new OleDbCommand();
// set the properties
objCommand.Connection = objConnect;
objCommand.CommandType = CommandType.Text;
objCommand.CommandText = strSelectBooks;
// create a new DataAdapter object
OleDbDataAdapter objDataAdapter = new OleDbDataAdapter();
// and assign the Command object to it
objDataAdapter.SelectCommand = objCommand;
// declare a variable to hold a DataTableMapping object
DataTableMapping objTableMapping;
// add the default table mapping "Table" - this table name will be used
// if you don't provide a table name when filling the DataSet
objTableMapping = objDataAdapter.TableMappings.Add("Table", "DefaultBookList");
// now add the column mappings for this table
objTableMapping.ColumnMappings.Add("ISBN", "BookCode");
objTableMapping.ColumnMappings.Add("Title", "BookTitle");
objTableMapping.ColumnMappings.Add("PublicationDate", "Published");
// add a table mapping so that data from the table named "BookAuthors" in
// the database will be placed in a table named "AuthorList"
objTableMapping = objDataAdapter.TableMappings.Add("BookAuthors", "AuthorList");
// add the column mappings for this table
objTableMapping.ColumnMappings.Add("ISBN", "BookCode");
objTableMapping.ColumnMappings.Add("FirstName", "Forename");
objTableMapping.ColumnMappings.Add("LastName", "Surname");
// new we're ready to fill a DataSet object from the database
// create a new DataSet object
DataSet objDataSet = new DataSet();
try
{
// get the data from the "BookList" table in the database and
// put it into a the default table in the DataSet object
objDataAdapter.Fill(objDataSet);
// change the SELECT statement in the Command object
objCommand.CommandText = strSelectAuthors;
// then get data from "BookAuthors" table in the database
// and put it into the mapped table in the DataSet
objDataAdapter.Fill(objDataSet, "BookAuthors");
}
catch (Exception objError)
{
// display error details
outError.InnerHtml = "<b>* Error while accesing data</b>.<br />"
+ objError.Message + "<br />" + objError.Source;
return; // and stop execution
}
// declare a variable to hold a DataRelation object
DataRelation objRelation;
// create a Relation object to link the two tables
// note that it uses the new mapped table and column names
objRelation = new DataRelation("BookAuthors",
objDataSet.Tables["DefaultBookList"].Columns["BookCode"],
objDataSet.Tables["AuthorList"].Columns["BookCode"]);
// and add it to the DataSet object's Relations collection
objDataSet.Relations.Add(objRelation);
// now we're ready to display the contents of the DataSet object
// bind the collection of Tables to the first DataGrid on the page
dgrTables.DataSource = objDataSet.Tables;
dgrTables.DataBind();
// bind the collection of Relations to the second DataGrid on the page
dgrRelations.DataSource = objDataSet.Relations;
dgrRelations.DataBind();
// create a DataView object to use with the tables in the DataSet
DataView objDataView = new DataView();
// get the default view of the default table into the DataView object
objDataView = objDataSet.Tables["DefaultBookList"].DefaultView;
// and bind it to the third DataGrid on the page
dgrBooksData.DataSource = objDataView;
dgrBooksData.DataBind();
// then do the same for the mapped BookAuthors table
objDataView = objDataSet.Tables["AuthorList"].DefaultView;
dgrAuthorsData.DataSource = objDataView;
dgrAuthorsData.DataBind();
}
</script>
<!--------------------------------------------------------------------------->
<!-- #include file="..\global\foot.inc" -->
</body>
</html>
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