Update README.md

README.md

@@ -35,6 +35,28 @@ var group = db.Queryable<Student>().GroupBy(it => it.Id)
 ``` 
 
 ### 1.3 Page
+
+#### easy join 
+
+```c
+//2 join
+var list5 = db.Queryable<Student, School>((st, sc) => st.SchoolId == sc.Id).Select((st,sc)=>new {st.Name,st.Id,schoolName=sc.Name}).ToList();
+```
+
+```c
+//3 join 
+var list6 = db.Queryable<Student, School,School>((st, sc,sc2) => st.SchoolId == sc.Id&&sc.Id==sc2.Id)
+    .Select((st, sc,sc2) => new { st.Name, st.Id, schoolName = sc.Name,schoolName2=sc2.Name }).ToList();
+ ```
+ 
+ ```c
+//3 join page
+var list7= db.Queryable<Student, School, School>((st, sc, sc2) => st.SchoolId == sc.Id && sc.Id == sc2.Id)
+.Select((st, sc, sc2) => new { st.Name, st.Id, schoolName = sc.Name, schoolName2 = sc2.Name }).ToPageList(1,2);
+```
+
+### left join  
+
 ```c
 var pageIndex = 1;
 var pageSize = 2;