DB2常用函数

1、char函数 

char(current date,ISO)——转换成yyyy-mm-dd 

char(current date,USA)——转换成mm/dd/yyyy 

char(current date,EUR)——转换成dd.mm.yyyy 



char(current date,JIS) 

char(current date,LOCAL) 



2、cast函数 

SELECT D.* FROM  wtp_pre_download AS D 

WHERE cast(D.arrivetime as bigint) >= cast('20090915122359000' as bigint) 

AND cast(D.arrivetime as bigint)  <=  cast('20090915235959999' as bigint) 



3、时间函数 



给定了日期、时间或时间戳，则使用适当的函数抽取出(如果适用的话)年、月、日、时、分、秒及微秒各部分： 



YEAR (current timestamp) 

MONTH (current timestamp) 

DAY (current timestamp) 

HOUR (current timestamp) 

MINUTE (current timestamp) 

SECOND (current timestamp) 

MICROSECOND (current timestamp) 



从时间戳单独抽取出日期和时间也非常简单： 



DATE (current timestamp) 

TIME (current timestamp) 



将字符串转换成日期或时间值，可以使用： 



TIMESTAMP ('2002-10-20-12.00.00.000000') 

TIMESTAMP ('2002-10-20 12:00:00') 

DATE ('2002-10-20') 

DATE ('10/20/2002') 

TIME ('12:00:00') 

TIME ('12.00.00') 

－－－－－ 

SELECT DECIMAL(CURRENT DATE)FROM SYSIBM.SYSDUMMY1; 

SELECT current date FROM sysibm.sysdummy1 

SELECT current time FROM sysibm.sysdummy1 

SELECT current timestamp FROM sysibm.sysdummy1 

－－－－－ 



使用英语(因为没有更好的术语)来执行日期和时间计算： 



current date + 1 YEAR 

current date + 3 YEARS + 2 MONTHS + 15 DAYS 

current time + 5 HOURS - 3 MINUTES + 10 SECONDS 



要计算两个日期之间相差的天数，您可以对日期作减法，例如： 



days (current date) - days (date('1999-10-22')) 



而以下示例描述了如何获得微秒部分归零的当前时间戳记： 



CURRENT TIMESTAMP - MICROSECOND (current timestamp) MICROSECONDS 



如果想将日期或时间值与其它文本相衔接，那么需要先将该值转换成字符串。为此，可以方便地使用CHAR()函数： 



char(current date) 

char(current time) 

char(current date + 12 hours)