[5分]运行“生成表查询”为何自动生成[%$##@_Alias]？

生成表查询的原始SQL代码如下：

SELECT ID, XM, JG INTO TABLEAAA
FROM (SELECT ID,XM,JG FROM [TABLE#1YG]
UNION
SELECT ID,KHMC AS XM, '' AS JG FROM [TABLE#2KH]) 

能正常运行，但运行后查看SQL代码，发现SQL代码自动变为如下：

SELECT [%$##@_Alias].ID, [%$##@_Alias].XM, [%$##@_Alias].JG INTO TABLEAAA
FROM (SELECT ID,XM,JG FROM [TABLE#1YG]
UNION
SELECT ID,KHMC AS XM, '' AS JG FROM [TABLE#2KH])  AS [%$##@_Alias];

问题：

1.[%$##@_Alias]是什么?

2.[%$##@_Alias]起什么作用?