网站怎么样制作视频网络营销学院

var list =db.Queryable<Student>()
.LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id)
.OrderBy((st,sc)=>st.SchoolId)//写Select前面用法，正常都这么用
.Select((st,sc)=>new Dto(){ id=it.id ,Name=it.Name})
.ToList();

var list =db.Queryable<Student>()
.LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id)
.Select((st,sc)=>new Dto(){ NewNum=st.Num+st.num2,Name=it.Name})
.MergeTable()//需要加上MergeTable对Select后的对象进行排序
.OrderBy(it=>it.NewNum)
.ToList();

OrderBy(it=>new {  it.Id, name=SqlFunc.Desc(it.Name) }).ToList();
//id asc ,name desc//也可以多个OrderBy
OrderBy(it=> it.Id).OrderBy(it=> SqlFunc.Desc(it.Name))

var list = db.Queryable<Student>().LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id)
.OrderBy(st=>st.Id)//升序
.OrderBy((st,sc)=>sc.Id,OrderByType.Desc)//写Select前面，写后面看标题1
.Select<ViewModelStudent>().ToList();
// order by st.id, sc.id desc  多级排序

//1.Sql字符串，可以防止低级成本注入,支持自定义重写SQL注入验证StaticConfig.Check_FieldFunc重写这个委托方法就可以
var list =db.Queryable<Student>()
.LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id)
.OrderBy("st.id asc,sc.Id desc ") //这种就是填SQL你SQL什么样就是什么样 建议看4.2用法
.Select<ViewModelStudent>().ToList();
//技巧可以通过方法转转拿到真实列名：EntityMaintenance.GetDbColumnName<Order>("Id") 100%防注入//2.属性名排序 ,100%防注入，他会根据类中的名字去验证是否存在，不存在就报错
var list= db.Queryable<Student>().OrderByPropertyName("Id").Toist();//有实体才能用这个，没有实体不能用这个//3.使用合并表排序                       
var list =db.Queryable<Student>()
.LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id)
.Select(it=>new {....})
.MergeTable()
.OrderByPropertyName("Id") //100%防注入，这样的好处可以去掉SQL的别名，适合多表排序
.ToList();

//新功能推荐
List<OrderByModel> orderList = OrderByModel.Create(  
new OrderByModel(){ FieldName="id",OrderByType=OrderByType.Desc},                     
new OrderByModel(){  FieldName="name"} //默认防注入：并且可以用StaticConfig.Check_FieldFunc重写验证机质
);     
var list=db.Queryable<Student>().AS("order").OrderBy(orderList).ToList();    //技巧：获取类中字段名FieldName=db.EntityMaintenance.GetDbColumnName<Order>("Id");//100%防注入

var pageJoin = db.Queryable<Student>().LeftJoin<School>((st, sc) =>st.SchoolId==sc.Id).Select((st, sc) => new {id = st.Id,name = sc.Name})
.MergeTable()//将查询结果集变成表MergeTable
.Where(it => it.id == 1).OrderBy("name asc").ToList();//对表MergeTable进行排序

select *  
from (select st.id as id,sc.name as name from xx join xx on ... ) MergeTable  --多表已经变成了单表where id=@idorder by ("name asc")

db.Queryable<Student>().Take(10).OrderBy(st=>SqlFunc.GetRandom()).ToList(); //随机获取数据

OrderByIF(IsOrderBy, it=>it.Id) //当条件IsOrderBy成立.OrderBy才生效

db.Queryable<Student>().Take(10).OrderBy(st=>SqlFunc.Desc(it.CreateTime)).ToList(); //order by createtime desc//也可以用这个重载
.OrderBy(it=>it.CreateTime,OrderByType.Desc)