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- 常用字符串函数
--字符函数
select
substr('abcdefg',1,5)substr, --字符串截取
instr('abcdefg','bc') instr, --查找子串
'Hello'||'World' concat, --连接
trim(' wish ') trim, --去前后空格
rtrim('wish ') rtrim, --去后面空格
ltrim(' wish') ltrim, --去前面空格
trim(leading 'w' from 'wish') deleteprefix, --去前缀
trim(trailing 'h' from 'wish') deletetrailing, --去后缀
trim('w' from 'wish') trim1,
ascii('A') A1,
ascii('a') A2, --ascii(转换为对应的十进制数)
chr(65) C1,
chr(97) C2, --chr(十进制转对应字符)
length('abcdefg') len, --length
lower('WISH')lower,
upper('wish')upper,
initcap('wish')initcap, --大小写变换
replace('zhangsan','1','lisi') replace, --替换
translate('zhangsan1','1','y')translate, --转换,对应一位(前面的位数大于等于后面的位数)
translate('wish1','sh1','hy')translate1,
concat('11','22') concat --连接
from dual;
--to_number
--to_number(expr)
--to_number(expr,format)
--to_number(expr,format,'nls-param')
- 常用日期函数
--日期
--年 yyyy yyy yy year
--月 month mm mon month
--日+星期 dd ddd(一年中第几天) dy day
--小时 hh hh24
--分 mi
--秒 ss
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss')currenttime,
to_char(sysdate,'yyyy') year,
to_char(sysdate,'mm') month,
to_char(sysdate,'dd') day,
to_char(sysdate,'day') week,
to_char(sysdate,'hh24')hour,
to_char(sysdate,'mi') minute,
to_char(sysdate,'ss') second
from dual;
select to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss')currenttime,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'yyyy')year,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'mm')month,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'dd') day,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'day') week,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'day','NLS_DATE_LANGUAGE=American') week, --设置语言
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'hh24')hour,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'mi') minute,
to_char(to_date('2009-07-04 05:02:01','yyyy-mm-dd hh24:mi:ss'),'ss') second
from dual;
--months_between
select months_between(to_date('03-31-2014','MM-DD-YYYY'),to_date('12-31-2013','MM-DD-YYYY')) "MONTHS"
FROM DUAL;
--next_day
select sysdate today, next_day(sysdate,6) nextweek from dual;
--时间区间
select cardid, borrowdate from borrow where to_date(borrowdate,'yyyy-mm-dd hh24:mi:ss')
between
to_date('2014-02-01 00:00:00','yyyy-mm-dd hh24:mi:ss') and
to_date('2014-05-01 00:00:00','yyyy-mm-dd hh24:mi:ss');
--interval 间隔
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') currenttime,
to_char(sysdate - interval '7' year,'yyyy-mm-dd hh24:mi:ss') intervalyear,
to_char(sysdate - interval '7' month,'yyyy-mm-dd hh24:mi:ss') intervalMonth,
to_char(sysdate - interval '7' day,'yyyy-mm-dd hh24:mi:ss') intervalday,
to_char(sysdate - interval '7' hour,'yyyy-mm-dd hh24:mi:ss') intervalHour,
to_char(sysdate - interval '7' minute,'yyyy-mm-dd hh24:mi:ss') intervalMinute,
to_char(sysdate - interval '7' second,'yyyy-mm-dd hh24:mi:ss') intervalSecond
from dual;
--add_months 增加月份
select add_months(sysdate,12) newtime from dual;
--extract
select extract(month from sysdate) "This Month",
extract(year from add_months(sysdate,36)) " Years" from dual;