Add demo

Src/Asp.NetCore2/SqlSeverTest/UserTestCases/UnitTest/UnitSubToList.cs

@@ -95,6 +95,19 @@ namespace OrmTest
                       NickName=SqlFunc.IIF(xx=="",it.NickName,it.NickName)
                      })
                  }, true).ToList();
+
+            var query4= db.Queryable<Demo_Comment>()
+              .Where(u => u.ArticleId == 100)
+               .Select(u => new SysCommentOutput
+               {
+                   SysUsers = SqlFunc.Subqueryable<Demo_User>()
+                   .Where(user => user.Id == u.UserId)
+                   .ToList(user => new SysUserOutput()
+                   {
+                       NickName= user.NickName,
+                       Id = u.UserId == 1 ? 1 : 2
+                   })
+               } ).ToList();
         }
 
         //评论表