diff --git a/Src/Asp.NetCore2/SqlSeverTest/UnitTest/Main.cs b/Src/Asp.NetCore2/SqlSeverTest/UnitTest/Main.cs
index e82eb7912..daa6bb210 100644
--- a/Src/Asp.NetCore2/SqlSeverTest/UnitTest/Main.cs
+++ b/Src/Asp.NetCore2/SqlSeverTest/UnitTest/Main.cs
@@ -31,6 +31,7 @@ namespace OrmTest
         }
         public static void Init()
         {
+            UCustom012.Init();
             UCustom01.Init();
             UCustom02.Init();
             UCustom03.Init();
diff --git a/Src/Asp.NetCore2/SqlSeverTest/UnitTest/UCustom012.cs b/Src/Asp.NetCore2/SqlSeverTest/UnitTest/UCustom012.cs
new file mode 100644
index 000000000..221f8b7d0
--- /dev/null
+++ b/Src/Asp.NetCore2/SqlSeverTest/UnitTest/UCustom012.cs
@@ -0,0 +1,80 @@
+ 
+using SqlSugar;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace OrmTest
+{
+    public class UCustom012
+    {
+
+        public static void Init()
+        {
+            var db = NewUnitTest.Db;
+
+            db.CodeFirst.InitTables<StudentA, RoomA, SchoolA>();
+            db.DbMaintenance.TruncateTable<StudentA>();
+            db.DbMaintenance.TruncateTable<RoomA>();
+            db.DbMaintenance.TruncateTable<SchoolA>();
+
+            db.Insertable(new RoomA() { RoomId = 1, RoomName = "北大001室", SchoolId = 1 }).ExecuteCommand();
+            db.Insertable(new RoomA() { RoomId = 2, RoomName = "北大002室", SchoolId = 1 }).ExecuteCommand();
+            db.Insertable(new RoomA() { RoomId = 3, RoomName = "北大003室", SchoolId = 1 }).ExecuteCommand();
+            db.Insertable(new RoomA() { RoomId = 4, RoomName = "清华001厅", SchoolId = 2 }).ExecuteCommand();
+            db.Insertable(new RoomA() { RoomId = 5, RoomName = "清华002厅", SchoolId = 2 }).ExecuteCommand();
+            db.Insertable(new RoomA() { RoomId = 6, RoomName = "清华003厅", SchoolId = 2 }).ExecuteCommand();
+
+
+            db.Insertable(new SchoolA() { SchoolId = 1, SchoolName = "北大" }).ExecuteCommand();
+            db.Insertable(new SchoolA() { SchoolId = 2, SchoolName = "清华" }).ExecuteCommand();
+
+            db.Insertable(new StudentA() { StudentId = 1, SchoolId = 1, Name = "北大jack" }).ExecuteCommand();
+            db.Insertable(new StudentA() { StudentId = 2, SchoolId = 1, Name = "北大tom" }).ExecuteCommand();
+            db.Insertable(new StudentA() { StudentId = 3, SchoolId = 2, Name = "清华jack" }).ExecuteCommand();
+            db.Insertable(new StudentA() { StudentId = 4, SchoolId = 2, Name = "清华tom" }).ExecuteCommand();
+
+            //先用Mapper导航映射查出第二层
+            var list = db.Queryable<StudentA>().Mapper(x => x.SchoolA, x => x.SchoolId).ToList();
+
+            //参数1 ：将第二层对象合并成一个集合  参数2：委托
+            //说明：如果2级对象是集合用SelectMany
+            db.ThenMapper(list.Select(it => it.SchoolA), sch =>
+            {
+                //参数1: room表关联字段  参数2: school表关联字段，  参数3: school当前记录
+                sch.RoomList = db.Queryable<RoomA>().SetContext(room => room.SchoolId, () => sch.SchoolId, sch).ToList();
+            });
+
+
+        }
+        public class StudentA
+        {
+            [SugarColumn(IsPrimaryKey = true)]
+            public int StudentId { get; set; }
+            public string Name { get; set; }
+            public int SchoolId { get; set; }
+            [SugarColumn(IsIgnore = true)]
+            public SchoolA SchoolA { get; set; }
+        }
+
+        public class SchoolA
+        {
+            [SugarColumn(IsPrimaryKey = true)]
+            public int SchoolId { get; set; }
+            public string SchoolName { get; set; }
+            [SugarColumn(IsIgnore = true)]
+            public List<RoomA> RoomList { get; set; }
+        }
+
+        public class RoomA
+        {
+            [SugarColumn(IsPrimaryKey = true)]
+            public int RoomId { get; set; }
+            public string RoomName { get; set; }
+            public int SchoolId { get; set; }
+        }
+
+    }
+}