将时间字符串转换为DATETIME类

-- 将时间字符串转换为DATETIME类
-- CASE1 
DECLARE @DD CHAR(8)= '20210114'
DECLARE @TT CHAR(6)= '082056'
SELECT CONVERT(DATETIME,CONVERT(CHAR(10),CONVERT(DATETIME, @DD,112),120)+' '+SUBSTRING(@TT,1,2)+':'+SUBSTRING(@TT,3,2)+':'+SUBSTRING(@TT,5,2))

-- CASE2
DECLARE @DT VARCHAR(20)= '20210114082056'
SELECT CONVERT(DATETIME,CONVERT(CHAR(10),CONVERT(DATETIME, LEFT(@DT,8),112),120)+' '+SUBSTRING(RIGHT(@DT,6),1,2)+':'+SUBSTRING(RIGHT(@DT,6),3,2)+':'+SUBSTRING(RIGHT(@DT,6),5,2))
--输出:2021-01-14 08:20:56.000

获取随机数

-- 生成1-10000范围内的随机数（0-9999范围内就用floor()）
select cast(ceiling(rand() * 10000) as int)    
select cast(ceiling(rand(checksum(newid()))*10000) as int) --基本同上，但是在批量更新时更合适