无法理解WITH…TempTable如何获取额外的行

我有一个叫Property2列的表PropertyRSN，ParentPropertyRSN

数据

propertyRSN | parentpropertyRSN
19          | 3
18          | 6
27          | 7
12          | 9
13          | 9
16          | 12

WITH tempTable(PLRSN, PRSN) AS (
   SELECT PropertyRSN, Property.ParentPropertyRSN 
   FROM Property 
   WHERE PropertyRSN = 16
   UNION ALL
   SELECT nplus1.PropertyRSN, nplus1.ParentPropertyRSN 
   FROM Property as nplus1, tempTable 
   WHERE tempTable.prsn = nplus1.PropertyRSN
)
SELECT PLRSN, PRSN 
FROM tempTable

结果

PLRSN | PRSN
16    | 12
12    | 9
9     | NULL

问题-我无法理解temTable查询如何获取包含数据的行9 | NULL？我也无法理解如何在方括号内使用TemTable？

================================================== ===================

create table property (propertyRSN int, ParentPropertyRSN int);
Insert into property (propertyRSN, ParentPropertyRSN) values (19,3);
Insert into property (propertyRSN, ParentPropertyRSN) values (18,6);
Insert into property (propertyRSN, ParentPropertyRSN) values (27,7);
Insert into property (propertyRSN, ParentPropertyRSN) values (12,9);
Insert into property (propertyRSN, ParentPropertyRSN) values (13,9);
Insert into property (propertyRSN, ParentPropertyRSN) values (16,12);