oracle常用函数汇总（分享）

oracle常⽤函数汇总（分享）
算术运算符：+ - * / 可以在select 语句中使⽤
连接运算符：|| select deptno|| dname from dept;
⽐较运算符：> >= = != < <= like between is null in
逻辑运算符：not and or
集合运算符： intersect ，union， union all， minus
对应集合的列数和数据类型相同
查询中不能包含long 列
列的标签是第⼀个集合的标签
使⽤order by时，必须使⽤位置序号，不能使⽤列名
例：集合运算符的使⽤：
复制代码代码如下:
intersect ，union， union all， minus
select * from emp intersect select * from emp where deptno=10 ;
select * from emp minus select * from emp where deptno=10;
select * from emp where deptno=10 union select * from emp where deptno in (10,20); --不包括重复⾏select * from emp where deptno=10 union all select * from emp where deptno in (10,20); --包括重复⾏ TO_DATE格式(以时间:2007-11-02 13:45:25为例)
Year:
yy two digits 两位年显⽰值:07
yyy three digits 三位年显⽰值:007
yyyy four digits 四位年显⽰值:2007
Month:
mm number 两位⽉显⽰值:11
mon abbreviated 字符集表⽰显⽰值:11⽉,若是英⽂版,显⽰nov
month spelled out 字符集表⽰显⽰值:11⽉,若是英⽂版,显⽰november
Day:
dd number 当⽉第⼏天显⽰值:02
ddd number 当年第⼏天显⽰值:02
dy abbreviated 当周第⼏天简写显⽰值:星期五,若是英⽂版,显⽰fri
day spelled out 当周第⼏天全写显⽰值:星期五,若是英⽂版,显⽰friday
ddspth spelled out, ordinal twelfth
Hour:
hh two digits 12⼩时进制显⽰值:01
hh24 two digits 24⼩时进制显⽰值:13
Minute:
mi two digits 60进制显⽰值:45
Second:
ss two digits 60进制显⽰值:25
其它
Q digit 季度显⽰值:4
WW digit 当年第⼏周显⽰值:44
W digit 当⽉第⼏周显⽰值:1
24⼩时格式下时间范围为： 0:00:00 - 23:59:59....
12⼩时格式下时间范围为： 1:00:00 - 12:59:59 ....
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') as nowTime from dual; //⽇期转化为字符串
select to_char(sysdate,'yyyy') as nowYear from dual; //获取时间的年
select to_char(sysdate,'mm') as nowMonth from dual; //获取时间的⽉
select to_char(sysdate,'dd') as nowDay from dual; //获取时间的⽇
select to_char(sysdate,'hh24') as nowHour from dual; //获取时间的时
select to_char(sysdate,'mi') as nowMinute from dual; //获取时间的分
select to_char(sysdate,'ss') as nowSecond from dual; //获取时间的秒
select to_date('2004-05-07 13:23:44','yyyy-mm-dd hh24:mi:ss') from dual//
显⽰Two Hundred Twenty-Two
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day') from dual;
星期⼀
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day','NLS_DATE_LANGUAGE = American') from dual; monday
设置⽇期语⾔
ALTER SESSION SET NLS_DATE_LANGUAGE='AMERICAN';
也可以这样
TO_DATE ('2002-08-26', 'YYYY-mm-dd', 'NLS_DATE_LANGUAGE = American')
select floor(sysdate - to_date('20020405','yyyymmdd')) from dual;
select id, active_date from table1
UNION
select 1, TO_DATE(null) from dual;
注意要⽤TO_DATE(null)
a_date between to_date('20011201','yyyymmdd') and to_date('20011231','yyyymmdd')
那么12⽉31号中午12点之后和12⽉1号的12点之前是不包含在这个范围之内的。

所以，当时间需要精确的时候，觉得to_char还是必要的
输⼊的格式要看你安装的ORACLE字符集的类型, ⽐如: US7ASCII, date格式的类型就是: '01-Jan-01'
alter system set NLS_DATE_LANGUAGE = American
alter session set NLS_DATE_LANGUAGE = American
或者在to_date中写
select to_char(to_date('2002-08-26','yyyy-mm-dd'),'day','NLS_DATE_LANGUAGE = American') from dual; 注意我这只是举了NLS_DATE_LANGUAGE，当然还有很多，
可查看
select * from nls_session_parameters
select * from V$NLS_PARAMETERS
复制代码代码如下:
select count(*)
from ( select rownum-1 rnum
from all_objects
where rownum <= to_date('2002-02-28','yyyy-mm-dd') - to_date('2002-
02-01','yyyy-mm-dd')+1
)
where to_char( to_date('2002-02-01','yyyy-mm-dd')+rnum-1, 'D' )
not in ( '1', '7' )
查找2002-02-28⾄2002-02-01间除星期⼀和七的天数
在前后分别调⽤DBMS_UTILITY.GET_TIME, 让后将结果相减(得到的是1/100秒, ⽽不是毫秒).
复制代码代码如下:
select months_between(to_date('01-31-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL;
1
select months_between(to_date('02-01-1999','MM-DD-YYYY'),to_date('12-31-1998','MM-DD-YYYY')) "MONTHS" FROM DUAL;
1.03225806451613
复制代码代码如下:
Next_day(date, day)
Monday-Sunday, for format code DAY
Mon-Sun, for format code DY
1-7, for format code D
select to_char(sysdate,'hh:mi:ss') TIME from all_objects
注意：第⼀条记录的TIME 与最后⼀⾏是⼀样的
可以建⽴⼀个函数来处理这个问题
复制代码代码如下:
create or replace function sys_date return date is
begin
return sysdate;
end;
select to_char(sys_date,'hh:mi:ss') from all_objects;
extract()找出⽇期或间隔值的字段值
复制代码代码如下:
SELECT EXTRACT(HOUR FROM TIMESTAMP '2001-02-16 2:38:40') from offer
SQL> select sysdate ,to_char(sysdate,'hh') from dual;
SYSDATE TO_CHAR(SYSDATE,'HH')
-------------------- ---------------------
2003-10-13 19:35:21 07
SQL> select sysdate ,to_char(sysdate,'hh24') from dual;
SYSDATE TO_CHAR(SYSDATE,'HH24')
-------------------- -----------------------
2003-10-13 19:35:21 19
复制代码代码如下:
select older_date,
newer_date,
years,
months,
abs(
trunc(
newer_date-
add_months( older_date,years*12+months )
)
) days
from ( select
trunc(months_between( newer_date, older_date )/12) YEARS,
mod(trunc(months_between( newer_date, older_date )),12 ) MONTHS,
newer_date,
older_date
from (
select hiredate older_date, add_months(hiredate,rownum)+rownum newer_date
from emp
)
)
select to_char(add_months(last_day(sysdate) +1, -2), 'yyyymmdd'),last_day(sysdate) from dual
select add_months(trunc(sysdate,'year'), 12) - trunc(sysdate,'year') from dual
闰年的处理⽅法
to_char( last_day( to_date('02' | | :year,'mmyyyy') ), 'dd' )
如果是28就不是闰年
复制代码代码如下:
'YYYY99 TO_C
------- ----
yyyy 99 0099
rrrr 99 1999
yyyy 01 0001
rrrr 01 2001
select to_char( NEW_TIME( sysdate, 'GMT','EST'), 'dd/mm/yyyy hh:mi:ss') ,sysdate
from dual;
复制代码代码如下:
Select TO_DATE(FLOOR(TO_CHAR(sysdate,'SSSSS')/300) * 300,'SSSSS') ,TO_CHAR(sysdate,'SSSSS') from dual
2002-11-1 9:55:00 35786
SSSSS表⽰5位秒数
select TO_CHAR(SYSDATE,'DDD'),sysdate from dual
310 2002-11-6 10:03:51
复制代码代码如下:
select
Days,
A,
TRUNC(A*24) Hours,
TRUNC(A*24*60 - 60*TRUNC(A*24)) Minutes,
TRUNC(A*24*60*60 - 60*TRUNC(A*24*60)) Seconds,
TRUNC(A*24*60*60*100 - 100*TRUNC(A*24*60*60)) mSeconds
from
(
select
trunc(sysdate) Days,
sysdate - trunc(sysdate) A
from dual
)
select * from tabname
order by decode(mode,'FIFO',1,-1)*to_char(rq,'yyyymmddhh24miss');
//
floor((date2-date1) /365) 作为年
floor((date2-date1, 365) /30) 作为⽉
d(mod(date2-date1, 365), 30)作为⽇.
返回下个星期的⽇期,day为1-7或星期⽇-星期六,1表⽰星期⽇
next_day(sysdate,6)是从当前开始下⼀个星期五。

后⾯的数字是从星期⽇开始算起。

1 2 3 4 5 6 7
⽇⼀⼆三四五六
---------------------------------------------------------------
select (sysdate-to_date('2003-12-03 12:55:45','yyyy-mm-dd hh24:mi:ss'))*24*60*60 from ddual
⽇期返回的是天然后转换为ss
select sysdate S1,
round(sysdate) S2 ,
round(sysdate,'year') YEAR,
round(sysdate,'month') MONTH ,
round(sysdate,'day') DAY from dual
select sysdate S1,
trunc(sysdate) S2, //返回当前⽇期,⽆时分秒
trunc(sysdate,'year') YEAR, //返回当前年的1⽉1⽇,⽆时分秒
trunc(sysdate,'month') MONTH , //返回当前⽉的1⽇,⽆时分秒
trunc(sysdate,'day') DAY //返回当前星期的星期天,⽆时分秒
from dual
select greatest('01-1⽉-04','04-1⽉-04','10-2⽉-04') from dual
注:oracle时间差是以天数为单位,所以换算成年⽉,⽇
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))/365) as spanYears from
dual //时间差-年
select ceil(moths_between(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))) as spanMonths from
dual //时间差-⽉
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))) as spanDays from dual //时间差-天
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24) as spanHours from dual //时间差-时
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24*60) as spanMinutes from dual //时间差-分
select floor(to_number(sysdate-to_date('2007-11-02 15:55:03','yyyy-mm-dd hh24:mi:ss'))*24*60*60) as spanSeconds from dual //时间差-秒
注:oracle时间加减是以天数为单位,设改变量为n,所以换算成年⽉,⽇
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),to_char(sysdate+n*365,'yyyy-mm-dd hh24:mi:ss') as newTime from dual //改变时间-年
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),add_months(sysdate,n) as newTime from dual //改变时间-⽉
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),to_char(sysdate+n,'yyyy-mm-dd hh24:mi:ss') as newTime from
dual //改变时间-⽇
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),to_char(sysdate+n/24,'yyyy-mm-dd hh24:mi:ss') as newTime from
dual //改变时间-时
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),to_char(sysdate+n/24/60,'yyyy-mm-dd hh24:mi:ss') as newTime from dual //改变时间-分
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss'),to_char(sysdate+n/24/60/60,'yyyy-mm-dd hh24:mi:ss') as newTime from dual //改变时间-秒
SELECT Trunc(Trunc(SYSDATE, 'MONTH') - 1, 'MONTH') First_Day_Last_Month,
Trunc(SYSDATE, 'MONTH') - 1 / 86400 Last_Day_Last_Month,
Trunc(SYSDATE, 'MONTH') First_Day_Cur_Month,
LAST_DAY(Trunc(SYSDATE, 'MONTH')) + 1 - 1 / 86400 Last_Day_Cur_Month
FROM dual;
select substr('abcdef',1,3) from dual
select instr('abcfdgfdhd','fd') from dual
select 'HELLO'||'hello world' from dual;
select ltrim(' abc') s1,
rtrim('zhang ') s2,
trim(' zhang ') s3 from dual
select trim(leading 9 from 9998767999) s1,
trim(trailing 9 from 9998767999) s2,
trim(9 from 9998767999) s3 from dual;
select ascii('a') from dual
select chr(97) from dual
select length('abcdef') from dual
select lower('ABC') s1,
upper('def') s2,
initcap('efg') s3
from dual;
select replace('abc','b','xy') from dual;
select translate('abc','b','xx') from dual; -- x是1位
select lpad('func',15,'=') s1, rpad('func',15,'-') s2 from dual;
select lpad(dname,14,'=') from dept;
注:第⼀个是表达式,最后⼀个是不满⾜任何⼀个条件的值
select deptno,decode(deptno,10,'1',20,'2',30,'3','其他') from dept;
例:
select seed,account_name,decode(seed,111,1000,200,2000,0) from t_userInfo//如果seed为111,则取1000;为200,取2000;其它取0
select seed,account_name,decode(sign(seed-111),1,'big seed',-1,'little seed','equal seed') from t_userInfo//如果seed>111,则显⽰⼤;为200,则显⽰⼩;其它则显⽰相等
复制代码代码如下:
SELECT CASE X-FIELD
WHEN X-FIELD < 40 THEN 'X-FIELD ⼩于 40'
WHEN X-FIELD < 50 THEN 'X-FIELD ⼩于 50'
WHEN X-FIELD < 60 THEN 'X-FIELD ⼩于 60'
ELSE 'UNBEKNOWN'
END
FROM DUAL
注:CASE语句在处理类似问题就显得⾮常灵活。

当只是需要匹配少量数值时，⽤Decode更为简洁。

select ceil(66.6) N1,floor(66.6) N2 from dual;
select power(3,2) N1,sqrt(9) N2 from dual;
select mod(9,5) from dual;
select round(66.667,2) N1,trunc(66.667,2) N2 from dual;
select sign(-32),sign(293) from dual;
1) select to_char(sysdate) s1,
to_char(sysdate,'yyyy-mm-dd') s2,
to_char(sysdate,'yyyy') s3,
to_char(sysdate,'yyyy-mm-dd hh12:mi:ss') s4,
to_char(sysdate, 'hh24:mi:ss') s5,
to_char(sysdate,'DAY') s6
from dual;
2) select sal,to_char(sal,'＄99999') n1,to_char(sal,'＄99,999') n2 from emp
insert into emp(empno,hiredate) values(8000,to_date('2004-10-10','yyyy-mm-dd'));
select to_number(to_char(sysdate,'hh12')) from dual; //以数字显⽰的⼩时数
返回登录的⽤户名称
select user from dual;
返回表达式所需的字节数
select vsize('HELLO') from dual;
ex1值为空则返回ex2,否则返回该值本⾝ex1（常⽤）
例：如果雇员没有佣⾦，将显⽰0，否则显⽰佣⾦
select comm,nvl(comm,0) from emp;
值相等返空，否则返回第⼀个值
例：如果⼯资和佣⾦相等，则显⽰空，否则显⽰⼯资
select nullif(sal,comm),sal,comm from emp;
返回列表中第⼀个⾮空表达式
select comm,sal,coalesce(comm,sal,sal*10) from emp;
如果ex1不为空，显⽰ex2,否则显⽰ex3
如：查看有佣⾦的雇员姓名以及他们的佣⾦
select nvl2(comm,ename,') as HaveCommName,comm from emp;
max min avg count sum
1) 求部门30 的最⾼⼯资，最低⼯资,平均⼯资，总⼈数，有⼯作的⼈数，⼯种数量及⼯资总和
复制代码代码如下:
select max(ename),max(sal),
min(ename),min(sal),
avg(sal),
count(*) ,count(job),count(distinct(job)) ,
sum(sal) from emp where deptno=30;
1)按部门分组求最⾼⼯资，最低⼯资，总⼈数，有⼯作的⼈数，⼯种数量及⼯资总和复制代码代码如下:
select deptno, max(ename),max(sal),
min(ename),min(sal),
avg(sal),
count(*) ,count(job),count(distinct(job)) ,
sum(sal) from emp group by deptno;
2)部门30的最⾼⼯资，最低⼯资，总⼈数，有⼯作的⼈数，⼯种数量及⼯资总和
复制代码代码如下:
select deptno, max(ename),max(sal),
min(ename),min(sal),
avg(sal),
count(*) ,count(job),count(distinct(job)) ,
sum(sal) from emp group by deptno having deptno=30;
select deptno,stddev(sal) from emp group by deptno;
variance 返回⼀组值的⽅差差
select deptno,variance(sal) from emp group by deptno;
rollup 按分组的第⼀个列进⾏统计和最后的⼩计
cube 按分组的所有列的进⾏统计和最后的⼩计
select deptno,job ,sum(sal) from emp group by deptno,job;
select deptno,job ,sum(sal) from emp group by rollup(deptno,job);
cube 产⽣组内所有列的统计和最后的⼩计
select deptno,job ,sum(sal) from emp group by cube(deptno,job);
只在会话期间或在事务处理期间存在的表.
临时表在插⼊数据时，动态分配空间
复制代码代码如下:
create global temporary table temp_dept
(dno number,
dname varchar2(10))
on commit delete rows;
insert into temp_dept values(10,'ABC');
commit;
select * from temp_dept; --⽆数据显⽰,数据⾃动清除
on commit preserve rows:在会话期间表⼀直可以存在（保留数据）
on commit delete rows:事务结束清除数据（在事务结束时⾃动删除表的数据）
除法：
复制代码代码如下:
select MOD(65,50) from dual --取余
select trunc( 65/33) from dual -- 取整 trunc (1.9) = 1
select ceil(65/60) from dual -- 取整 ceil(1.1) = 2。