计算时间列所在年的周序号

 

需求描述

需求：对EMP表里员工KING和SMITH的hiredate入职时间差，基于生成的日期算每天所在的周，相对于年.

解决方法:通过DATE_FORMAT函数来完成.

注: 数据库数据集SQL脚本详见如下链接地址

员工表结构和数据初始化SQL脚本

SQL代码

-- Mysql： SELECT B.ename b_Ename,B.HIREDATE b_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-1 AS pos FROM tb_incr) seq WHERE A.ename = 'SMITH' AND B.ename = 'KING' AND seq.pos <=DATEDIFF(B.HIREDATE,A.HIREDATE)

注：mysql里也可以通过yearweek函数来实现

-- mysql SELECT YEARWEEK(now()) 'yearWeek', SUBSTRING(YEARWEEK(now()),1,4)'year', SUBSTRING(YEARWEEK(now()),5,2) 'weekOfyear'

 

执行结果

-- 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)

 

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