基于文件名的数据列表显示项

Question

This question to related to a similar Data list question I posted some days ago. I have a datalist which displays Categories, and then documents within categories. What needs to happen is that documents under each category gets displayed in the order based on some numbers in file names. Documents are in format like '001-filename.pdf', '002-filename.pdf' ... '00x-filename.pdf'. I can use the first dash as some kind of 'split' function then grab the numbers like '001' etc to make the sorting to work. I think this could be done on either itemdatabound or in the sql syntax. I am posting the relevant code here. Any idea as to how I can make this to work? It is possible that there could be more than one document with shared number prefix: '001-filename.pdf', '001-filenameversion2.pdf' etc. Thanks!

ASPX:

<asp:DataList ID="DataList1" runat="server" RepeatDirection="Vertical" DataKeyField="docid"
    EnableViewState="True" OnItemDataBound="DataList1_ItemDataBound">
    <ItemTemplate>
        <table cellpadding="0" cellspacing="0" id="tbl_data">
            <tr runat="server" id="tr_category">
                <td>
                    <asp:Label ID="lblHeader" runat="server" Font-Bold="True" Text='<%# Eval("categoryname") %>'
                        Font-Underline="True"></asp:Label>
                    <asp:Label runat="server" ID="lbl_cb_all">Select All
                        <asp:CheckBox runat="server" OnCheckedChanged="CheckAllChanged" AutoPostBack="true"
                            ID="cb_selectall" />
                    </asp:Label>
                    <asp:HiddenField ID="HiddenCatID" runat="server" Value='<%# Eval("CatID") %>' />
                    <asp:HiddenField ID="HiddenDocID" runat="server" Value='<%# Eval("docid") %>' />
                </td>
            </tr>
            <tr runat="server" id="tr_data">
                <td>
                    <asp:CheckBox runat="server" ID="cb_docid" Value='<%# Eval("docid") %>' OnCheckedChanged="displayselectedinit"
                        AutoPostBack="true" />
                    <asp:HyperLink ID="hpl_docfileencr" Text='<%# Eval("docfileencr") %>' NavigateUrl='<%# "~/PDFEncr/" + DataBinder.Eval(Container.DataItem, "docfileencr") %>'
                        Target="_blank" runat="server" />
                    <br />
                </td>
            </tr>
        </table>
    </ItemTemplate>
</asp:DataList>

C# CodeBehind:

sqlsyntax = @"SELECT  dbo.projectsdocuments.docfileencr,dbo.categories.catid, dbo.categories.categoryname, dbo.projectsdocuments.docid
              FROM dbo.Projects INNER JOIN dbo.projectsdocuments ON (dbo.Projects.projectid = dbo.projectsdocuments.projectid)
              INNER JOIN dbo.categories ON (dbo.projectsdocuments.categoryid = dbo.categories.catid)
              WHERE  Projects.projectid = " + projectid + " ORDER BY dbo.categories.sortorder ASC";

protected void DataList1_ItemDataBound(Object sender, DataListItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        var row = (DataRowView)e.Item.DataItem;
        var view = row.DataView;
        var lastRow = e.Item.ItemIndex == 0 ? null : view[e.Item.ItemIndex - 1];
        var tr_category = (System.Web.UI.HtmlControls.HtmlTableRow)e.Item.FindControl("tr_category");
        var sameCategory = lastRow != null && (int)row["catid"] == (int)lastRow["catid"];
        tr_category.Visible = !sameCategory;
    }
}

Answer 1

Change your ORDER BY to include both columns.

SELECT  
    dbo.projectsdocuments.docfileencr,
    dbo.categories.catid, 
    dbo.categories.categoryname, 
    dbo.projectsdocuments.docid
FROM dbo.Projects 
INNER JOIN dbo.projectsdocuments 
    ON (dbo.Projects.projectid = dbo.projectsdocuments.projectid)
INNER JOIN dbo.categories 
    ON (dbo.projectsdocuments.categoryid = dbo.categories.catid)
WHERE  Projects.projectid = " + projectid + "
ORDER BY dbo.categories.sortorder, dbo.projectsdocuments.docfileencr

The order by precedence is left to right, the default is "ASCENDING" but you can change a specific column sort by adding "ASC or DESC" directly after it.

** IMPORTANT NOTE **

Your code is susceptible to SQL Injection because your doing string concatenation. If this is a concern to you, change the SQL statement to use a named parameter that you assign using a command parameter (see example below).

Step 1: Change the inline string parameter, to a named parameter "@projectid".

SELECT  
    dbo.projectsdocuments.docfileencr,
    dbo.categories.catid, 
    dbo.categories.categoryname, 
    dbo.projectsdocuments.docid
FROM dbo.Projects 
INNER JOIN dbo.projectsdocuments 
    ON (dbo.Projects.projectid = dbo.projectsdocuments.projectid)
INNER JOIN dbo.categories 
    ON (dbo.projectsdocuments.categoryid = dbo.categories.catid)
 WHERE  Projects.projectid = @projectid
 ORDER BY dbo.categories.sortorder, dbo.projectsdocuments.docfileencr

Step 2: Assign the parameter inline (example code)

using(SqlConnection conn = new SqlConnection(connString))
{
    conn.Open();

    SqlCommand command = new SqlCommand(sql, conn);
    command.CommandType = CommandType.Text;

    // Assign the value projectid to the parameter @projectid
    command.Parameters.Add(new SqlParameter("@projectid", projectid));

    // Execute The Command (fill dataset, create datareader, etc...)
    SqlDataReader reader = command.ExecuteReader();
}