select case when [am or _pm] ='PM' and datepart(HOUR,time_received)<>12 
           then dateadd(hour,12,time_received) 
           else time_received 
       END 
from table

作品

DATEPART()函数用于返回日期/时间的单个部分，如年、月、日、小时、分钟等。

datepart    ***Abbreviation

year        ***yy, yyyy 
quarter     ***qq, q 
month       ***mm, m 
dayofyear   ***dy, y 
day         ***dd, d 
week        ***wk, ww 
weekday     ***dw, w 
hour        ***hh 
minute      ***mi, n 
second      ***ss, s 
millisecond ***ms 
microsecond ***mcs 
nanosecond  ***ns 

例子

select * 
from table001
where datepart(hh,datetime) like 23

SELECT DATEPART(HOUR, GETDATE());

DATEPART文档

select case when [am or _pm] ='PM' and datepart(HOUR,time_received)<>12 
           then dateadd(hour,12,time_received) 
           else time_received 
       END 
from table

作品

必须使用datepart()

like 


datepart(hour , getdate())

DATEPART(HOUR， [date])返回军事时间的小时(00到23) 如果你想要凌晨1点，下午3点等等，你需要区分:

SELECT Run_Time_Hour =
CASE DATEPART(HOUR, R.date_schedule)
    WHEN 0 THEN  '12AM'
    WHEN 1 THEN   '1AM'
    WHEN 2 THEN   '2AM'
    WHEN 3 THEN   '3AM'
    WHEN 4 THEN   '4AM'
    WHEN 5 THEN   '5AM'
    WHEN 6 THEN   '6AM'
    WHEN 7 THEN   '7AM'
    WHEN 8 THEN   '8AM'
    WHEN 9 THEN   '9AM'
    WHEN 10 THEN '10AM'
    WHEN 11 THEN '11AM'
    WHEN 12 THEN '12PM'
    ELSE CONVERT(varchar, DATEPART(HOUR, R.date_schedule)-12) + 'PM'
END
FROM
    dbo.ARCHIVE_RUN_SCHEDULE R