WITH语句相当于建立了一张临时虚拟表，但是不会被物理创建，用完即销毁。

示例

利用临时表生成连续的数字表

WITH 
T1 AS(
	SELECT n = 1
	UNION ALL
	SELECT n = 1
), --2条
T2 AS (
	SELECT n = 1
	FROM T1 A
	CROSS JOIN T1 B
), --4条
T3 AS (
	SELECT n = 1
	FROM T2 A
	CROSS JOIN T2 B
), --16条
T4 AS (
	SELECT n = 1
	FROM T3 A
	CROSS JOIN T3 B
), --256条
T5 AS (
	SELECT n = 1
	FROM T4 A
	CROSS JOIN T4 B
) --(2的(N-1)次方)的平方
SELECT A.RN
FROM(
	SELECT ROW_NUMBER() OVER(ORDER BY n) RN
	FROM T5
) A
WHERE A.RN < 10000

示例

利用INTO直接新建一个临时表存select出来的数据

select * into #xxxx from A 

SQL的临时表