column-constraints.aspx

来自「东软内部材料（四）asp等相关的教学案例　」· ASPX 代码 · 共 97 行

ASPX

97 行

<%@Page Language="C#"%>

<%@Import Namespace="System.Data" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head>
<title>Adding Expressions, Default Values and Constraints to a Table</title>
<!-- #include file="..\global\style.inc" -->
</head>
<body bgcolor="#ffffff">
<span class="heading">Adding Expressions, Default Values and Constraints to a Table</span><hr />
<!--------------------------------------------------------------------------->

<asp:datagrid id="dgrResult" runat="server" />

<script language="C#" runat="server">

	void Page_Load(Object sender, EventArgs e)
	{
		// create a new empty DataTable object
		DataTable objTable = new DataTable("NewBooks");

		// declare a variable to hold a DataColumn object
		DataColumn objColumn;

		// define the columns (fields) within the table
		// the first is an AutoIncrement column to act as the key
		objColumn = objTable.Columns.Add("kBookKey", Type.GetType("System.Int32"));
		objColumn.AutoIncrement = true;
		objColumn.AutoIncrementSeed = 1000;
		objColumn.AutoIncrementStep = 10;

		// next, the ISBN column which must be unique and not allow Null values
		objColumn = objTable.Columns.Add("ISBN", Type.GetType("System.String"));
		objColumn.AllowDBNull = false;
		objColumn.Unique = true;
		objColumn.MaxLength = 10;

		// now two more columns to hold general information
		objTable.Columns.Add("Title", Type.GetType("System.String"));
		objTable.Columns.Add("PublicationDate", Type.GetType("System.DateTime"));

		// add two columns to hold stock and order quantities, with default values of zero
		objColumn = objTable.Columns.Add("StockQty", Type.GetType("System.Int32"));
		objColumn.DefaultValue = 0;
		objColumn = objTable.Columns.Add("OrderedQty", Type.GetType("System.Int32"));
		objColumn.DefaultValue = 0;

		// add a column containing an expression showing the quantity availability
		objColumn = objTable.Columns.Add("AvailableQty", Type.GetType("System.Int32"));
		objColumn.Expression = "[StockQty] - [OrderedQty]";

		// declare a variable to hold a DataRow object
		DataRow objDataRow;

		// create a new DataRow object instance in this table
		objDataRow = objTable.NewRow();

		// and fill in the values
		objDataRow["ISBN"] = "1234567800";
		objDataRow["Title"] = "Professional Video Recorder Programming";
		objDataRow["PublicationDate"] = new DateTime(2001, 03, 01);
		objDataRow["StockQty"] = 3956;
		objDataRow["OrderedQty"] = 450;
		objTable.Rows.Add(objDataRow);

		// repeat to add two more rows
		objDataRow = objTable.NewRow();
		objDataRow["ISBN"] = "1234567801";
		objDataRow["Title"] = "Professional WAP Phone Programming";
		objDataRow["PublicationDate"] = new DateTime(2001, 06, 01);
		objDataRow["StockQty"] = 329;
		// note - no "OrderedQty" provided so default value used
		objTable.Rows.Add(objDataRow);

		objDataRow = objTable.NewRow();
		objDataRow["ISBN"] = "1234567802";
		objDataRow["Title"] = "Professional Radio Station Programming";
		objDataRow["PublicationDate"] = new DateTime(2001, 04, 01);
		// note - no "StockQty" provided so default value used
		objDataRow["OrderedQty"] = 1200;
		objTable.Rows.Add(objDataRow);

		// assign the DataTable's DefaultView object to the DataGrid control
		dgrResult.DataSource = objTable.DefaultView;
		dgrResult.DataBind();  // and bind (display) the data

	}
	
</script>


<!--------------------------------------------------------------------------->
<!-- #include file="..\global\foot.inc" -->
</body>
</html>

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