LINQ查询
一、条件查询
1.||查询
//方式一 var list = from message in sel.one where message.id == "1" || message.score == "60" select message; //方式二 var list = sel.one.Where(r=>r.id=="1"||r.score=="60");
2.&&查询
//方式一 var list = from message in sel.one where message.id == "1" && message.score == "50" select message; //方式二 var list = sel.one.Where(r => r.id == "1" && r.score == "60");
二、模糊查询
1.包含(任意位置)
//方式一 var list = from message in sel.one where message.score.Contains("5") select message; //方式二 var list = sel.one.Where(r => r.score.Contains("5"));
2.开头
//方式一 var list = from message in sel.one where message.score.StartsWith("5") select message; //方式二 var list = sel.one.Where(r => r.score.StartsWith("5"));
3.结尾
//方式一 var list = from message in sel.one where message.score.EndsWith("5") select message; //方式二 var list = sel.one.Where(r => r.score.EndsWith("5"));
三、统计查询
1.个数
var count = con.car.Count();
2.最大值
var Max = con.car.Max(r => r.price);
3.最小值
var Min = con.car.Min(r => r.price);
4.平均值
var avg = con.car.Average(r => r.price);
四、分页查询
int count = 5;//每页显示的条数 int page = 1;//页码 var list = sel.one.Skip(page*count).Take(count);//绑定数据
五、排序查询
1.升序
//方式一 var list = from message in sel.one orderby message.score ascending select message;//orderby 子句默认是升序 //方式二 var list = sel.one.OrderBy(r=>r.score);
2.降序
//方式一 var list = from message in sel.one orderby message.score descending select message; //方式二 var list = sel.one.OrderByDescending(r => r.score);
六、外键显示
return this.brand1.brand_name;
七、组合查询
var list = list1.Intersect(list2).Intersect(list3);//符合list1和list2还有list3的三种查询条件的查询