SQL生成一年每一天的时间列表的几种方法

Posted 2020-09-14 大唐过客

工作好几年了，一直没有写博客，准备捡起来。。。

 

以下脚本适用环境：SQL SERVER （starting with 2012）

 

1、构建序列：

 

/*1-1：利用交叉连接，推荐下列这种写法*/

 

SELECT
/*2012 开始已支持OFFSET 语法，不再推荐使用TOP N */
s1.i + s2.i + s3.i + s4.i + s5.i + s6.i + s7.i + s8.i + s9.i AS seq
FROM ( SELECT i = 0 UNION ALL SELECT i = 1 ) s1
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 2 as i) s2
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 4 as i) s3
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 8 as i) s4
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 16 as i) s5
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 32 as i) s6
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 64 as i ) s7
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 128 as i ) s8
CROSS JOIN ( SELECT 0 as i UNION ALL SELECT 256 as i ) s9
ORDER BY seq
OFFSET 0 ROWS FETCH NEXT 366 ROWS ONLY

 

 

/* 1-2：如果系统表列数不够或者过多，会对结果或性能有影响 */

 

SELECT ROW_NUMBER() OVER (ORDER BY a1.object_id) - 1 AS seq
FROM sys.all_columns a1 WITH ( NOLOCK ) ,
sys.all_columns a2 WITH ( NOLOCK )
ORDER BY seq
OFFSET 0 ROWS FETCH NEXT 366 ROWS ONLY

 

 

/* 1-3：循环，不推荐的写法 */

 

DECLARE @I INT

DECLARE @seq TABLE
(
seq INT NOT NULL
)

SET @I=0

WHILE @I < 366
BEGIN

INSERT INTO @seq(seq)
VALUES(@I)

SET @I+=1

END

SELECT * FROM @seq

 

 

 

2、基于以上的任意一种序列，使用DATEADD(DAY,seq,@DstDate) 即可生成一年中的每一天的时间列表。

 

 

3、拓展：mysql中如何利用以上的思路，在不编写存储过程或函数的前提下，利用SQL 语句拆分一个字符串到数组？

 

点此传送查看答案>>>