Linq学习__05__查询表达式和方法查询比较

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（1）在HomeController中新建Index3方法如代码1.1

代码1.1

#region 用查询表达式和方法查询实现同样的查询
        /// <summary>
        /// 访问地址 Home/Index3
        /// orderby,Where(),OrderBy(),OrderByDescending()
        /// </summary>
        /// <returns></returns>
        public ActionResult Index3()
        {
            //*********************************第一组开始*********************************
            int[] numbers = { 5, 10, 8, 3, 6, 12 };
            //用查询表达式
            IEnumerable<int> numQuery1 =from num in numbers
                                        where num % 2 == 0
                                        orderby num ascending//默认是升序ascending,可以不写
                                        select num;
            ViewBag.numQuery1 = numQuery1;
            //用方法查询
            IEnumerable<int> numQuery2 = numbers.Where(num => num % 2 == 0).OrderBy(n => n);//默认是升序OrderBy
            ViewBag.numQuery2 = numQuery2;
            //*********************************第一组结束*********************************

            //*********************************第二组开始*********************************
            var numQuery3 = from num in numbers
                            orderby num descending//降序descending
                            where num > 5 && num < 13
                            select num;
            ViewBag.numQuery3 = numQuery3;

            var numQuery4 = numbers.Where(num => (num > 5 && num < 13)).OrderByDescending(n => n);//降序OrderByDescending,升序可不是OrderByAscending,而是OrderBy
            ViewBag.numQuery4 = numQuery4;
            //*********************************第二组结束*********************************

            //*********************************第三组开始*********************************
            var numQuery5 = from num in numbers
                            where num > 10 || num <= 6
                            select num;
            ViewBag.numQuery5 = numQuery5;

            var numQuery6 = numbers.Where(num => (num > 10 || num <= 6));
            ViewBag.numQuery6 = numQuery6;
            //*********************************第三组结束*********************************
            //*********************************第四组开始*********************************
            //*********************************第四组结束*********************************
            //*********************************第五组开始*********************************
            //*********************************第五组结束*********************************
            

            return View();
        }
        #endregion 用查询表达式和方法查询实现同样的查询

2）添加视图Index3.cshtml，代码如代码1.2
代码1.2

 

@{
    ViewBag.Title = "Index3";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
@{
    <div style=" background-color: pink;">第一组：查询能被2整除的数</div>
    <div style=" background-color: Yellow;">
        用查询表达式where orderby</div>
    foreach (var i in ViewBag.numQuery1)
    {
    <div>@i</div>   
    }
    <div style=" background-color: Yellow;">
        用方法查询where orderby</div>
    foreach (var j in ViewBag.numQuery2)
    {
    <div>@j</div>   
    }
    
    <div style=" background-color: pink;">第二组：查询大于5小于13的数</div>
    <div style=" background-color: Yellow;">
        用查询表达式where与运算符&&</div>
    foreach (var k in ViewBag.numQuery3)
    {
    <div>@k</div>   
    }
        <div style=" background-color: Yellow;">
        用方法查询where与运算符&&</div>
    foreach (var m in ViewBag.numQuery4)
    {
    <div>@m</div>   
    }
    <div style=" background-color: pink;">第三组:查询大于10或小于等于6的数</div>
        <div style=" background-color: Yellow;">
        用查询表达式或运算符||</div>
    foreach (var n in ViewBag.numQuery5)
    {
    <div>@n</div>   
    }
        <div style=" background-color: Yellow;">
        用方法查询或运算符||</div>
    foreach (var p in ViewBag.numQuery6)
    {
    <div>@p</div>   
    }
    <div style=" background-color: pink;">第四组</div>
    <div style=" background-color: pink;">第五组</div>
    }