特别请教@q107770540，关于动态组合条件查询的问题
特别请教@q107770540，以下为完整控制台代码，粘贴后可以直接运行。
按照查询条件，理想的输出产品应为P1、P2、P4，但这里的结果却不对，请问为什么呢？谢谢！

C# code

using System;using System.Collections.Generic;using System.Linq;using System.Linq.Expressions;using System.Text;namespace LinqTest{    // 产品信息    class Product    {        public int CategoryId { get; set; }        public string Name { get; set; }        public float Price { get; set; }    }    // 产品价格范围条件    class PriceCondition    {        public string Name { get; set; }        public float Min { get; set; }        public float Max { get; set; }    }    class Program    {        static List<Product> _products = new List<Product>();    //产品列表        static void Main(string[] args)        {            //添加产品数据            _products.Add(new Product() { CategoryId = 1, Name = "P1", Price = 50 });            _products.Add(new Product() { CategoryId = 2, Name = "P2", Price = 80 });            _products.Add(new Product() { CategoryId = 3, Name = "P3", Price = 100 });            _products.Add(new Product() { CategoryId = 2, Name = "P4", Price = 120 });            _products.Add(new Product() { CategoryId = 4, Name = "P5", Price = 200 });            //生成价格范围查询条件            List<PriceCondition> priceRange = new List<PriceCondition>();            priceRange.Add(new PriceCondition() { Name = "100元以下", Min = 0, Max = 100 });            priceRange.Add(new PriceCondition() { Name = "150～180元", Min = 150, Max = 180 });            //查询并输出            List<Product> result = Search("", new List<int> { 1, 2, 3 }, priceRange);            foreach(Product pdt in result)                Console.WriteLine("Name:{0}, CateId:{1}, Price:{2}", pdt.Name, pdt.CategoryId, pdt.Price);            Console.ReadLine();        }        //实现T-SQL效果:    select * from product        //                where Name like '%keyword%'        //                and CategoryId in(1,2,3)        //                and ((price<100) || (price>=150 and price<180))        static List<Product> Search(string keyword, List<int> cateIds, List<PriceCondition> priceRange)        {            Expression<Func<Product, bool>> expression = PredicateExtensions.True<Product>();            if (!string.IsNullOrEmpty(keyword))                expression = expression.And(p => p.Name.Contains(keyword));            if (cateIds != null && cateIds.Count > 0)                expression = expression.And(p => cateIds.Contains(p.CategoryId));            if (priceRange != null && priceRange.Count > 0)            {                foreach (PriceCondition pc in priceRange)                {                    /////////////此处正确写法应该是什么呢？                    if (pc.Max > 0)                        expression = expression.Or(p => p.Price >= pc.Min && p.Price < pc.Max);                    else                        expression = expression.Or(p => p.Price >= pc.Min);                }            }            return _products.Where(expression.Compile()).ToList();        }    }    static class PredicateExtensions    {        public static Expression<Func<T, bool>> True<T>() { return f => true; }        public static Expression<Func<T, bool>> False<T>() { return f => false; }        public static Expression<Func<T, bool>> Or<T>(            this Expression<Func<T, bool>> expression1,            Expression<Func<T, bool>> expression2            )        {            var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>());            return Expression.Lambda<Func<T, bool>>(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters);        }        public static Expression<Func<T, bool>> And<T>(            this Expression<Func<T, bool>> expression1,            Expression<Func<T, bool>> expression2        )        {            var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>());            return Expression.Lambda<Func<T, bool>>(Expression.And(expression1.Body, invokedExpression), expression1.Parameters);        }    }} 
 

[解决办法]
以前问过。http://topic.csdn.net/u/20120814/17/6a25779f-d16e-465a-8fdf-2d0c1ecbc7e9.html
应该不会有P4
[解决办法]
http://www.cnblogs.com/whitewolf/archive/2010/08/02/1790390.html

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