想要一个查询在 Linq 查询中按变量排序 [英] want a Query to make order by variable in Linq query

问题描述

如何按列变量排序，因为我在页面上有一个下拉列表，我想根据此下拉列表中选择的排序显示网格，例如价格、代码、评级、描述等，我不想单独编写查询每一列.

How to make order by Column variable because I have a dropdown on page and I want to show grid according to sord order selected in this Dropdown e.g Price, Code, rating, description etc etc. and I donot want to write a separate query for each column.

from lm in lDc.tbl_Products
where lm.TypeRef == pTypeId
 orderby lm.Code ascending
 select new; 

推荐答案

假设您想通过 SQL 进行排序，那么您需要传入排序列/类型.查询会推迟到您实际执行选择之后，以便您可以分步构建查询，完成后像这样执行:

Assuming you want to do the sorting via SQL then you will need to pass in the sort column/type. The query is deferred until you actually do the select so you can build up the query in steps and once you are done execute it like so:

// Do you query first.  This will NOT execute in SQL yet.
var query = lDC.tbl_Products.Where(p => p.TypeRef == pTypeId);

// Now add on the sort that you require... you could do ascending, descending,
// different cols etc..
switch (sortColumn)
{
    case "Price":
        query = query.OrderBy(q => q.Price);
        break;
    case "Code":
        query = query.OrderBy(q => q.Code);
        break;
    // etc...
}

// Now execute the query to get a result
var result = query.ToList();

如果您想在 SQL 之外执行此操作，则只需获得不进行排序的基本结果，然后根据您需要的排序条件将 OrderBy 应用于结果.

If you want to do it outside of SQL then just get a basic result with no sorting and then apply an OrderBy to the result base on the sort criteria you need.

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