Question

我正在使用带有c＃的SqlDataSource控件。 ASP.NET 3.5 Visual Studio 2013。

我有两个下拉列表控件，其中包含使用ORDER BY进行排序的值，以及SqlDataSource查询中的以下order by子句...

select ... ORDER BY @sortfield @order

@sortfield是DropDownList中作为Filterparameter的值的表字段的名称，而@order是从SqlDataSource FilterParameter的其他DropDownList值中选择的ASC或DESC。

它明确地在运行时替换值，因为返回的错误是：

语法错误：'ASC'运算符后缺少操作数

或者，如果FilterParams字段留空并且变量只放在查询中

@order operator

之后的语法不正确

如果它没有返回错误 - 那么结果集为空（但是删除order by子句并且查询返回结果集！）

我尝试添加分号和各种引号和括号，但无济于事。

我还尝试将FilterExpression设置为{0} {1}并使用ORDER BY结束查询 - 但这更糟糕。

为什么语法错误？使用带有ORDER BY子句的FilterParams是否有问题？

这是SqlDataSource代码。注意我这里没有使用过滤器表达式，但这似乎更糟糕了：

<asp:SqlDataSource ID="sqlds_copy_1" runat="server" ConnectionString="<%$ ConnectionStrings:abConnectionString %>"
    OnInit="sqlds_copy_1_Init" OnPreRender="sqlds_copy_1_PreRender"
    SelectCommand="SELECT ab_genericentry.title, ab_genericentry.heading, ab_genericentry.body, ab_genericentry.time, ab_genericentry.date, ab_genericentry.header, ab_genericentry.synopsis, ab_genericentry.abstract, ab_genericentry.footer, ab_genericentry.introduction, ab_genericentry.conclusion, ab_genericentry.headline, ab_genericentry.release_date, ab_copyinstances.control_name FROM ab_pages INNER JOIN ab_sites ON ab_pages.site_id = ab_sites.id INNER JOIN ab_copyinstances ON ab_pages.id = ab_copyinstances.page_id AND ab_sites.id = ab_copyinstances.site_id INNER JOIN ab_genericentry ON ab_copyinstances.id = ab_genericentry.copy_instance_id WHERE (ab_sites.site_name LIKE 'philaxiom') AND (ab_copyinstances.control_name LIKE 'dl_copy_1') AND (ab_pages.page_url LIKE '/pa_home.aspx')

ORDER BY [@sortfield] [@order]“＆gt;

这里使用的是使用{0} {1}的过滤器表达式，但这会在第二个参数上使用：语法错误：'ASC'运算符后缺少操作数。

所以FilterParams值会进入，但解析器不喜欢表达式的结尾。我不知道为什么。

我再次使用下拉列表中的值字段，但SqlDataSource FilterParameters属性中的向导似乎只允许使用值 - 而不是文本：

<asp:SqlDataSource ID="sqlds_copy_1" runat="server" ConnectionString="<%$ ConnectionStrings:abConnectionString %>"
    OnInit="sqlds_copy_1_Init" OnPreRender="sqlds_copy_1_PreRender"
    SelectCommand="SELECT ab_genericentry.title, ab_genericentry.heading, ab_genericentry.body, ab_genericentry.time, ab_genericentry.date, ab_genericentry.header, ab_genericentry.synopsis, ab_genericentry.abstract, ab_genericentry.footer, ab_genericentry.introduction, ab_genericentry.conclusion, ab_genericentry.headline, ab_genericentry.release_date, ab_copyinstances.control_name FROM ab_pages INNER JOIN ab_sites ON ab_pages.site_id = ab_sites.id INNER JOIN ab_copyinstances ON ab_pages.id = ab_copyinstances.page_id AND ab_sites.id = ab_copyinstances.site_id INNER JOIN ab_genericentry ON ab_copyinstances.id = ab_genericentry.copy_instance_id WHERE (ab_sites.site_name LIKE 'philaxiom') AND (ab_copyinstances.control_name LIKE 'dl_copy_1') AND (ab_pages.page_url LIKE '/pa_home.aspx')

ORDER BY“FilterExpression =”{0} {1}“＆gt;

这个使用上面的FilterParams属性，但使用[@sortfield] [@order]。 IOt给出了语法错误：'[@order]'运算符后缺少操作数：

   <asp:SqlDataSource ID="sqlds_copy_1" runat="server" ConnectionString="<%$ ConnectionStrings:abConnectionString %>"
    OnInit="sqlds_copy_1_Init" OnPreRender="sqlds_copy_1_PreRender"
    SelectCommand="SELECT ab_genericentry.title, ab_genericentry.heading, ab_genericentry.body, ab_genericentry.time, ab_genericentry.date, ab_genericentry.header, ab_genericentry.synopsis, ab_genericentry.abstract, ab_genericentry.footer, ab_genericentry.introduction, ab_genericentry.conclusion, ab_genericentry.headline, ab_genericentry.release_date, ab_copyinstances.control_name FROM ab_pages INNER JOIN ab_sites ON ab_pages.site_id = ab_sites.id INNER JOIN ab_copyinstances ON ab_pages.id = ab_copyinstances.page_id AND ab_sites.id = ab_copyinstances.site_id INNER JOIN ab_genericentry ON ab_copyinstances.id = ab_genericentry.copy_instance_id WHERE (ab_sites.site_name LIKE 'philaxiom') AND (ab_copyinstances.control_name LIKE 'dl_copy_1') AND (ab_pages.page_url LIKE '/pa_home.aspx')

ORDER BY“FilterExpression =”[@ sortfield] [@order]“＆gt;

DROP DOWN LISTS CONTROLS：

 <asp:DropDownList ID="ddl_SortField" runat="server" AppendDataBoundItems="True">
            <asp:ListItem Value="ab_genericentry.title" Selected="True">Entry Name</asp:ListItem>
            <asp:ListItem Value="ab_genericentry.date">Entry Date</asp:ListItem>
</asp:DropDownList>
        <asp:DropDownList ID="ddl_Order" runat="server">
            <asp:ListItem Value="DESC">↓</asp:ListItem>
            <asp:ListItem Value="ASC" Selected="True">↑</asp:ListItem>
        </asp:DropDownList>

Answer 1

对于初学者，您可能希望用方括号括起@sortfield，以消除列名中有空格导致语法错误（Missing operand after 'Operator Name' operator）的可能性。
另外，您是使用下拉框中的正确值设置参数（即文本而不是值）？不幸的是，如果没有能够看到更多的代码，很难给出更直接的答案。

代码隐藏示例：

1）将更改事件添加到排序下拉列表

asp：DropDownList ID =“ddl_SortField”runat =“server”AppendDataBoundItems =“True”OnSelectedIndexChanged =“ddl_SortField_SelectedIndexChanged”

2）代码隐藏

   protected void ddl_SortField_SelectedIndexChanged(object sender, EventArgs e)
   {
       var sqlCommand = string.Format("SELECT ab_genericentry.title, ab_genericentry.heading, ab_genericentry.body, " +
           "ab_genericentry.time, ab_genericentry.date, ab_genericentry.header, ab_genericentry.synopsis, " +
           "ab_genericentry.abstract, ab_genericentry.footer, ab_genericentry.introduction, ab_genericentry.conclusion, " +
           "ab_genericentry.headline, ab_genericentry.release_date, ab_copyinstances.control_name " +
           "FROM ab_pages " +
           "INNER JOIN ab_sites ON ab_pages.site_id = ab_sites.id " +
           "INNER JOIN ab_copyinstances ON ab_pages.id = ab_copyinstances.page_id AND ab_sites.id = ab_copyinstances.site_id " +
           "INNER JOIN ab_genericentry ON ab_copyinstances.id = ab_genericentry.copy_instance_id " +
           "WHERE (ab_sites.site_name LIKE 'philaxiom') AND (ab_copyinstances.control_name LIKE 'dl_copy_1') " +
           "AND (ab_pages.page_url LIKE '/pa_home.aspx')" +
           "ORDER BY [{0}] {1}", ddl_SortField.SelectedValue.ToString(),
           ddl_Order.SelectedValue.ToString());

       sqlds_copy_1.SelectCommand = sqlCommand;
   }

带有ORDER BY CLAUSE的SqlDataSource.FilterParams FilterExpression

1 个答案: