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SQL基础操作_7_时间运算

發布時間：2024/9/27 数据库 19 豆豆

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7.8 時間運算

7.8.1 對時間列進行加減

7.8.2 計算兩個時間列的差值

7.8.3 計算兩個時間列工作日差值

7.8.4 計算時間列所在的周的序號

7.8.5 計算時間列所在年的周序號

7.8 時間運算

注:數據集和表結構見?SQL基礎操作_1_檢索數據

7.8.1 對時間列進行加減

需求：對EMP表里員工編號為7369的hiredate按照天、月、年各加.

解決方法:通過DATEADD函數來完成.

SQL Server:

SELECT empno,hiredate,DATEADD(DAY,1,hiredate) next_Day, DATEADD(MONTH,1,hiredate) next_Month, DATEADD(YEAR,1,hiredate) next_Year FROM emp WHERE empno = 7369

執行結果：

empno	hiredate	next_Day	next_Month	next_Month
7369	1980-12-17	1980-12-18	1981-01-17	1981-12-17

MySQL:

SELECT empno,hiredate,DATE_ADD(hiredate,INTERVAL1DAY) AS next_Day, DATE_ADD(hiredate,INTERVAL1MONTH) AS next_Day, DATE_ADD(hiredate,INTERVAL1 YEAR) AS next_Day FROM emp WHERE empno=7369

7.8.2 計算兩個時間列的差值

需求：對EMP表里員工KING和SMITH的hiredate入職時間差，這里單位是分鐘、小時、天、周、月、年.

解決方法:通過DATEDIFF函數來完成.

Mysql：

SELECT B.ename b_Ename,B.HIREDATEb_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate, TIMESTAMPDIFF(MINUTE,A.HIREDATE,B.HIREDATE)minute_diff, TIMESTAMPDIFF(HOUR,A.HIREDATE,B.HIREDATE)hour_diff, DATEDIFF(B.HIREDATE,A.HIREDATE) day_diff, TIMESTAMPDIFF(WEEK,A.HIREDATE,B.HIREDATE)week_diff,TIMESTAMPDIFF(MONTH,A.HIREDATE,B.HIREDATE)month_diff, TIMESTAMPDIFF(YEAR,A.HIREDATE,B.HIREDATE) year_diff FROM emp A,emp B WHERE A.ename ='SMITH'AND B.ename ='KING'

執行結果：

b_Ename	b_hiredate	a_Ename	a_hiredate	minute_diff	hour_diff	day_diff	week_diff	month_diff	year_diff
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	482400	8040	335	47	11	0

SQL Server：

SELECT B.ename b_Ename,B.HIREDATE b_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,DATEDIFF(MINUTE,A.HIREDATE,B.HIREDATE) minute_Diff ,DATEDIFF(HOUR,A.HIREDATE,B.HIREDATE) hour_Diff ,DATEDIFF(DAY,A.HIREDATE,B.HIREDATE) day_Diff ,DATEDIFF(WEEK,A.HIREDATE,B.HIREDATE) week_Diff ,DATEDIFF(MONTH,A.HIREDATE,B.HIREDATE) month_Diff ,DATEDIFF(YEAR,A.HIREDATE,B.HIREDATE) year_Diff FROM emp A,emp B WHERE A.ename = 'SMITH' AND B.ename = 'KING'

執行結果:

b_Ename	b_hiredate	a_Ename	a_hiredate	minute_Diff	hour_Diff	day_Diff	week_Diff	month_Diff	year_Diff
KING	1981-11-17	SMITH	1980-12-17	482400	8040	335	48	11	1

7.8.3 計算兩個時間列工作日差值

需求：對EMP表里員工KING和SMITH的hiredate入職時間差，這里單位是天且是工作日時間，即周末不計算在內.

解決方法:通過DATEDIFF函數來完成.

SQL Serer：

SELECT B.ename b_Ename,B.HIREDATE b_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,SUM(CASE WHEN DATENAME(DW,DATEADD(DAY,seq.pos,A.HIREDATE)) IN('星期六','星期日') THEN 0 ELSE 1 END) AS workday_Num FROM emp A,emp B,(SELECT number AS pos FROM master.[dbo].[spt_values] WHERE type = 'P') seq WHERE A.ename = 'SMITH' AND B.ename = 'KING' AND seq.pos <= DATEDIFF(DAY,A.HIREDATE,B.HIREDATE) GROUP BY B.ename ,B.HIREDATE,A.ename , A.HIREDATE

執行結果：

b_Ename	b_hiredate	a_Ename	a_hiredate	workday_Num
KING	1981-11-17	SMITH	1980-12-17	240

Mysql：

SELECT B.ename b_Ename,B.HIREDATEb_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate, SUM(CASE WHEN DATE_FORMAT(DATE_ADD(A.hiredate,INTERVAL pos DAY),'%w') IN (0,6) THEN 0 ELSE 1 END) AS workday_Num FROM emp A,emp B,(SELECT i-1 AS pos FROM tb_incr) seq WHERE A.ename ='SMITH'AND B.ename ='KING'AND seq.pos <=DATEDIFF(B.HIREDATE,A.HIREDATE) GROUPBY B.ename,B.HIREDATE,A.ename , A.HIREDATE

執行結果：

b_Ename	b_hiredate	a_Ename	a_hiredate	workday_Num
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	240

7.8.4 計算時間列所在的周的序號

需求：對EMP表里員工KING和SMITH的hiredate入職時間差，基于生成的日期算每天所在的周序號.

解決方法:通過DATE_FORMAT函數來完成.

SQL Server:

SELECT B.ename b_Ename,B.HIREDATE b_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,DATEADD(DAY,seq.pos,A.HIREDATE) AS date_Seq ,CASE DATEPART(DW,DATEADD(DAY,seq.pos,A.HIREDATE)) WHEN 1 THEN '星期日'WHEN 2 THEN '星期一'WHEN 3 THEN '星期二'WHEN 4 THEN '星期三'WHEN 5 THEN '星期四'WHEN 6 THEN '星期五'WHEN 7 THEN '星期六' END ASweekno FROM emp A,emp B,(SELECT number AS pos FROM master.[dbo].[spt_values] WHERE type = 'P') seq WHERE A.ename = 'SMITH' AND B.ename = 'KING' AND seq.pos <= DATEDIFF(DAY,A.HIREDATE,B.HIREDATE)-- 或者借助datename函數 SELECT B.ename b_Ename,B.HIREDATE b_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,DATEADD(DAY,seq.pos,A.HIREDATE) AS date_Seq ,DATENAME(DW,DATEADD(DAY,seq.pos,A.HIREDATE)) AS weekno FROM emp A,emp B,(SELECT number AS pos FROM master.[dbo].[spt_values] WHERE type = 'P') seq WHERE A.ename = 'SMITH' AND B.ename = 'KING' AND seq.pos <= DATEDIFF(DAY,A.HIREDATE,B.HIREDATE)

執行結果:

b_Ename	b_hiredate	a_Ename	a_hiredate	date_Seq	weekno
KING	1981-11-17	SMITH	1980-12-17	1980-12-17	星期三
KING	1981-11-17	SMITH	1980-12-17	1980-12-18	星期四
KING	1981-11-17	SMITH	1980-12-17	1980-12-19	星期五
KING	1981-11-17	SMITH	1980-12-17	1980-12-20	星期六
KING	1981-11-17	SMITH	1980-12-17	1980-12-21	星期日
KING	1981-11-17	SMITH	1980-12-17	1980-12-22	星期一
KING	1981-11-17	SMITH	1980-12-17	1980-12-23	星期二
…	…	…	…	…	…

注:函數DATEPART(DW,DateValue)返回周序號,如果是星期日則是返回 1,是星期六則是7.

Mysql:

SELECT B.ename b_Ename,B.HIREDATEb_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate, CASE DATE_FORMAT(DATE_ADD(A.hiredate,INTERVAL pos DAY),'%w') WHEN 0 THEN '周日' WHEN 1 THEN '星期一' WHEN 2 THEN '星期二' WHEN 3 THEN '星期三' WHEN 4 THEN '星期四' WHEN 5 THEN '星期五' WHEN 6 THEN '星期六' END AS weekno FROM emp A,emp B,(SELECT i-1AS pos FROM tb_incr) seq WHERE A.ename ='SMITH'AND B.ename ='KING'AND seq.pos <=DATEDIFF(B.HIREDATE,A.HIREDATE)

結果同上.

7.8.5 計算時間列所在年的周序號

需求：對EMP表里員工KING和SMITH的hiredate入職時間差，基于生成的日期算每天所在的周，相對于年.

解決方法:通過DATE_FORMAT函數來完成.

Mysql：

SELECT B.ename b_Ename,B.HIREDATEb_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,DATE_ADD(A.hiredate,INTERVAL pos DAY) date_Seq ,DATE_FORMAT(DATE_ADD(A.hiredate,INTERVAL pos DAY),'%U') AS weekno_Year FROM emp A,emp B,(SELECT i-1AS pos FROM tb_incr) seq WHERE A.ename ='SMITH'AND B.ename ='KING'AND seq.pos <=DATEDIFF(B.HIREDATE,A.HIREDATE)

執行結果:

b_Ename	b_hiredate	a_Ename	a_hiredate	date_Seq	weekno_Year
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/17 0:00:00	50
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/18 0:00:00	50
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/19 0:00:00	50
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/20 0:00:00	50
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/21 0:00:00	51
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/22 0:00:00	51
KING	1981/11/17 0:00:00	SMITH	1980/12/17 0:00:00	1980/12/23 0:00:00	51

SQL Server:

SELECT B.ename b_Ename,B.HIREDATE b_hiredate,A.ename a_Ename, A.HIREDATE a_hiredate ,DATEADD(DAY,seq.pos,A.HIREDATE) AS date_Seq ,DATEPART(WK,DATEADD(DAY,seq.pos,A.HIREDATE)) AS weekno_Year FROM emp A,emp B,(SELECT number AS pos FROM master.[dbo].[spt_values] WHERE type = 'P') seq WHERE A.ename = 'SMITH' AND B.ename = 'KING' AND seq.pos <= DATEDIFF(DAY,A.HIREDATE,B.HIREDATE)

執行結果:

b_Ename	b_hiredate	a_Ename	a_hiredate	date_Seq	weekno_Year
KING	1981-11-17	SMITH	1980-12-17	1980-12-17	51
KING	1981-11-17	SMITH	1980-12-17	1980-12-18	51
KING	1981-11-17	SMITH	1980-12-17	1980-12-19	51
KING	1981-11-17	SMITH	1980-12-17	1980-12-20	51
KING	1981-11-17	SMITH	1980-12-17	1980-12-21	52
KING	1981-11-17	SMITH	1980-12-17	1980-12-22	52
KING	1981-11-17	SMITH	1980-12-17	1980-12-23	52
KING	1981-11-17	SMITH	1980-12-17	1980-12-24	52
...	...	...	...	...	...

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