c#中如何使用到模糊查询

c#中如何使用到模糊查询,先举个最简单实用的例子，可在vs控制台应用程序中输出：

定义实体类：

 public class student
        {
            public int id { get; set; }

            public string name { get; set; }

            public int? age { get; set; }

            public string sex { get; set; }
        }

 

为实体类赋值存放到集合list中：

 list<student> lsstudent = new list<student>(){
                new student { id = 1,name = "1", age = 128, sex = null },
                new student { id = 2, name = "2", age = 18, sex = "女" },
                new student { id = 3, name = "31", age = 13, sex = "男" },
                new student { id = 4, name = "4", age = 23, sex = "男" },
                new student { id = 5, name = "51", age = null, sex = "女" },
                new student { id = 6, name = "6", age = null, sex = "女" },
                new student { id = 7, name = "7", age = null, sex = "女" }

            };

模糊查询条件：根据name=1或者sex=女模糊查询

   string key = "1";
   string sex = "女";

  方法一：linq

   list<student> resultlist = (from c in lsstudent where  c.name.contains(key) ||c.sex.contains(sex) select c).tolist();

  知识讲解：

  1,contains("key"),---意义等同于ql server中的like '%key%'，从两端模糊匹配

  2,startswith("key"),---意义等同于sql server中的like 'key%',从开头模糊匹配

  3,endswith("key"),---意义等同于sql server中的like '%key',从结尾模糊匹配

 

 方法二：
   list<student> resultlist = lsstudent.where(str => str.name.contains(key) || str.sex.contains(key)).tolist();

 

  方法三：
   list<student> resultlist = (from c in lsstudent where c.name.indexof(key)>=0 ||c.sex.indexof(sex)>=0 select c).tolist();

  知识讲解：

  1，c.name.indexof(key)>=0 ---意义等同于 like '%key%',从两端模糊匹配

  2，c.name.startswith(key) ---等同于like 'key%' ,从开头模糊匹配

  3，c.name.endwith(key) ---等同于like '%key',从结尾模糊匹配

  vs控制台输出打印代码：

 

  string json = jsonconvert.serializeobject(resultlist, newtonsoft.json.formatting.indented);
  console.writeline(json);