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//写法1
var queryable=db.Queryable<Order>();
var list=db.Queryable(queryable).LeftJoin<OrderDetails>((o,d)=>o.id==d.orderid).Select(o=>o).ToList();//写法2
db.Queryable<Order>().Select<Order>()//mergetable之前要有Select.MergeTable()//合并成一个表 (MergeTable之前不能有OrderBy)
.LeftJoin<OrderDetails>((o,d)=>o.id==d.orderid).Select(o=>o).ToList();//5.1.3.41版本只有Where可以不写MergeTable
db.Queryable<Order>().Where(it=>o.id==1)
.LeftJoin<OrderDetails>((o,d)=>o.id==d.orderid).Select(o=>o).ToList();//匿名对象看标题2

var queryableRight = db.Queryable<OrderItem>().Where(x => x.OrderId > 0);
var list=db.Queryable<Order>().LeftJoin(queryableRight,(o,d)=>o.Id == d.OrderId).Select(o=>o).ToList();

 var q11 = db.Queryable<Order>().Where(it => it.Id>1);var q22 = db.Queryable<Order>().Where(it => it.Id > 2);var q33 = db.Queryable<Order>().Where(it => it.Id > 3);var list= q11.LeftJoin(q22, (x, y) => x.Id == y.Id).LeftJoin(q33, (x, y, z) => x.Id == z.Id).ToList();

var query1 = db.Queryable<Student, School>((st, sc) => new JoinQueryInfos(JoinType.Left,st.SchoolId==sc.Id)).Where(st => st.Name == "jack");var query2 = db.Queryable<DataTestInfo>();db.Queryable(query1, query2,JoinType.Left, (p1, p2) => p1.Id == p2.Int1).Select<ViewModelStudent>().ToList();//SELECT * FROM //    (SELECT          [st].[ID],[st].[SchoolId],[st].[Name],[st].[CreateTime] //                  FROM [STudent] st //                Left JOIN [School] sc ON ([st].[SchoolId]=[sc].[Id] )   //               WHERE ( [st].[Name] = @Name0Join0 ))  p1 ////  LEFT JOIN// (SELECT          [Int1],[Int2],[String],[Decimal1],[Decimal2],//                [Datetime1],[Datetime2],[Image1],[Image2], //               [Guid1],[Guid2],[Money1],[Money2],[Varbinary1],//                  [Varbinary2],[Float1],[Float2] FROM [DataTestInfo] )p2   //     ON ( [p1].[ID] = [p2].[Int1] )

 //SqlQueryable就是一个Sql转成Queryablevar list= db.SqlQueryable<Student>("select * from student").Where(it=>it.Id==1).ToPageList(1, 2);//具体用例：db.Queryable<Order>().LeftJoin(db.SqlQueryable<Custom>("select * from Custom"), (o, i) => o.CustomId == i.Id) .Select(o => o).ToList();//SELECT o.* FROM [Order] o Left JOIN (select * from Custom) i ON ( [o].[CustomId] = [i].[Id] )//5.1.3.41支持了反过来用
db.SqlQueryable<Custom>("select * from Custom").LeftJoin...

 var queryable = db.Reportable(List<实体>).ToQueryable();var list= db.Queryable<Order>().InnerJoin(queryable, (x1, x2) => x1.Id == x2.OrderId).Select((x1, x2) => new { name = x1.Name, id = x1.Id, orderid = x2.OrderId }).ToList();

//单个匿名对象JOIN
//注意： 如果有OrderBy请写在MergeTable后面
db.Queryable<Order>().Select(it => new { id = it.Id })//匿名对象.MergeTable()//合并成新表 MergeTable 和 OrderItem 进行JOIN.LeftJoin<OrderItem>((x, y) => x.id == y.ItemId) //最后一个表不能是匿名对象.ToList();//技巧：如果匿名对象在右边  可以把 LeftJoin 换成 RightJoin 变相就实现了 
//多个匿名对象JOIN看下面//多个匿名对象Join 
//注意： 如果有OrderBy请写在MergeTable后面   
db.Queryable<Order>().Select(it => new { id = it.Id })//匿名对象.MergeTable()//合并 .LeftJoin<OrderItem>((x, y) => x.id == y.ItemId) //联表.Select((x, y) => new {xid=x.id,yid=y.ItemId})//在次转成匿名对象.ToList(); //老版本用法
var query1 = db.Queryable<Order, OrderItem>((o, i) => new JoinQueryInfos(JoinType.Left, o.Id == i.OrderId)).Where(o => o.Name == "jack");var query2 = db.Queryable<Custom>()//转成Object.Select<object>(it=>new { id=1});var list3=db.Queryable(query1, query2,JoinType.Left, //query2是匿名对象所以p2.id用字符串实现(p1, p2) => p1.CustomId == SqlFunc.MappingColumn(default(int),"p2.id")).Select<ViewOrder>().ToList();

var pageJoin = db.Queryable<Student, School>((st, sc) => new JoinQueryInfos(JoinType.Left,st.SchoolId==sc.Id)).Select((st,sc) => new{ id = st.Id,name = sc.Name}).MergeTable() //在mergetale之前不能有排序 分页 skip take操作，之后可以.Where(it=>it.id==1).OrderBy("name asc").ToList();

SELECT * FROM (SELECT  [st].[Id] AS [id] , [sc].[Name] AS [name]  FROM [Student] st Left JOIN [School] sc ON ( [st].[SchoolId] = [sc].[Id] )  ) MergeTable--将结果变成一个表  WHERE ( [id] = @id0 )ORDER BY name asc

//三种写法结果一样的//写法1:
var subQuery=db.Queryable<Order>().Select(it=>new xxx{....});
var list=db.Queryable(subQuery).ToList();//写法2:
var list=db.Queryable<Order>().SelectMergeTable(it=>new xxx{....}).ToList();//高版本可以用这个（WithTempQuery）//写法3:
var list=db.Queryable<Order>().Select(it=>new xxx{....}).MergeTable().ToList();//也可以分开写

SELECT t.* FROM  (SELECT [Id],[Name],[Price],[CreateTime],[CustomId] FROM [Order] ) t

db.QuryableWithAttr<T>().LeftJoin<T2>(...).ToList();//切换成库不会改主表名 (leftJoin部分一样的)

db.Quryable<T>().AsWithAttr().LeftJoin<T2>(...).ToList();//不是当前库改表名不切换库  (leftJoin部分一样的)

var q1=db.Queryable<UnitNClobTest>().AsWithAttr(); 
var q2=db.Queryable<UnitNClobTest>().AsWithAttr(); 
//如果用QuryableWithAttr他们如果有切换库操作 表名也不会变，所以要用AsWithAttr强势变表名
db.UnionAll(q1, q2).ToList();