oracle函数学习
SQL> select substr('liuyuehui',3) as first_name from dual;
FIRST_NAME
--------------
uyuehui
SQL> select substr('liuyuehui',1) as first_name from dual;
FIRST_NAME
------------------
liuyuehui
SQL> select substr('liuyuehui',0) as first_name from dual;
FIRST_NAME
------------------
liuyuehui
SQL> select substr('liuyuehui',-3,3) from dual;
SUBSTR
------
hui
SQL> select substr('liuyuehui',length('liuyuehui')-5) as first_name from dual;
FIRST_NAME
------------
yuehui
SQL> select substr('feng',lenth('feng')-1) from dual;
select substr('feng',lenth('feng')-1) from dual
*
第 1 行出现错误:
ORA-00904: "LENTH": 标识符无效
SQL> select substr('feng',length('feng')-1) from dual;
SUBS
----
ng
SQL> select substr('liufeng',3,7) as firstname,substr('liufeng',-4,4) as secondn
ame from dual;
FIRSTNAME SECONDNA
---------- --------
ufeng feng
SQL> select substr('liufeng',0,3) as firstname,substr('liufeng',-4,4) as secondn
ame from dual;
FIRSTN SECONDNA
------ --------
liu feng
SQL> select upper(substr('liufeng',0,3) ) as firstname,lower(substr('liuyuehui',
3)) as secondname from dual;
FIRSTN SECONDNAME
------ --------------
LIU uyuehui
SQL> select upper(substr('liufeng',0,3) ) as firstname,lower(substr('liuyuehui',
4)) as secondname from dual;
FIRSTN SECONDNAME
------ ------------
LIU yuehui
SQL> select instr('Hello World!','or') from dual;
INSTR('HELLOWORLD!','OR')
-------------------------
8
SQL> select trim(' hello ') from dual;
TRIM('HELL
----------
hello
SQL> select trim(' hello ') as hi from dual;
HI
----------
hello
SQL> select lpad('smith',10,'*') from dual;
LPAD('SMITH',10,'*')
--------------------
*****smith
SQL> select lpad('smith',10,'*') as star_smith from dual;
STAR_SMITH
--------------------
*****smith
SQL> select rpad('smith',10,'*') as star_smith from dual;
STAR_SMITH
--------------------
smith*****
SQL> select rpad('smith',10,'*') as reft_star_smith,lpad('smith',10,'*') as righ
t_star_smith from dual;
REFT_STAR_SMITH RIGHT_STAR_SMITH
-------------------- --------------------
smith***** *****smith
SQL> select substr(instr('testmyname','or'),-4,4) from dual;
S
-
SQL>
SQL> select substr(instr('testmyname','or'),-4,4) from dual;
S
-
SQL> select instr('testmyname','or') from dual;
INSTR('TESTMYNAME','OR')
------------------------
0
SQL> select instr('test myname','or') from dual;
INSTR('TESTMYNAME','OR')
------------------------
0
SQL> select rpad('smith',10,'月') as reft_star_smith,lpad('smith',10,'*') as rig
ht_star_smith from dual;
REFT_STAR_SMITH RIGHT_STAR_SMITH
------------------------ --------------------
smith月月 *****smith
SQL> select rpad('smith',10,'月') as reft_star_smith,lpad('smith',10,'月') as ri
ght_star_smith from dual;
REFT_STAR_SMITH RIGHT_STAR_SMITH
------------------------ ------------------------
smith月月 月月smith
SQL> select next_day(sysdate,'星期一') from dual;
NEXT_DAY(SYSDA
--------------
19-1月 -15
SQL> select next_day(sysdate,'星期天') from dual;
select next_day(sysdate,'星期天') from dual
*
第 1 行出现错误:
ORA-01846: 周中的日无效
SQL> select next_day(sysdate,'星期日') from dual;
NEXT_DAY(SYSDA
--------------
18-1月 -15
SQL> select last_day(sysdate) from dual;
LAST_DAY(SYSDA
--------------
31-1月 -15
SQL> select add_months(sysdate,1) from dual;
ADD_MONTHS(SYS
--------------
14-2月 -15
SQL> select add_months(sysdate,1) as next_month from dual;
NEXT_MONTH
--------------
14-2月 -15
SQL> select to_char(sysdate,'yyyy') from dual;
TO_CHAR(
--------
2015
SQL> select to_char(sysdate,'mmmm') from dual;
TO_CHAR(
--------
0101
SQL> select to_char(sysdate,'mm') from dual;
TO_C
----
01
SQL> select to_char(sysdate,'mm-ss') from dual;
TO_CHAR(SY
----------
01-52
SQL> select to_char(sysdate,’D’) from dual;//返回星期
2
SQL> select to_char(sysdate,’D’) from dual;
select to_char(sysdate,’D’) from dual
*
第 1 行出现错误:
ORA-01756: 引号内的字符串没有正确结束
SQL> select to_char(sysdate,'D') from dual;
TO
--
4
SQL> Select to_date(„20090210‟,‟yyyyMMdd‟) from dual;
Select to_date(?20090210?,?yyyyMMdd?) from dual
*
第 1 行出现错误:
ORA-00911: 无效字符
SQL> Select to_date('20090210"‟,‟yyyyMMdd‟) from dual;
ERROR:
ORA-01756: 引号内的字符串没有正确结束
SQL> Select to_date('20090210'‟,‟yyyyMMdd‟) from dual;
Select to_date('20090210'?,?yyyyMMdd?) from dual
*
第 1 行出现错误:
ORA-00911: 无效字符
SQL> Select to_date('20090210',yyyyMMdd‟) from dual;
Select to_date('20090210',yyyyMMdd?) from dual
*
第 1 行出现错误:
ORA-00911: 无效字符
SQL> Select to_date('20090210','yyyyMMdd'‟) from dual;
Select to_date('20090210','yyyyMMdd'?) from dual
*
第 1 行出现错误:
ORA-00911: 无效字符
SQL> Select to_date('20090210','yyyyMMdd') from dual;
TO_DATE('20090
--------------
10-2月 -09
SQL> select empno, ename, sal,
2 case deptno
3 when 10 then '财务部'
4 when 20 then '研发部'
5 when 30 then '销售部'
6 else '未知部门'
7 end 部门
8 from emp;
from emp
*
第 8 行出现错误:
ORA-00942: 表或视图不存在
SQL> select empno, lpad(initcap(trim(ename)),10,' ') name, job, sal from emp;
select empno, lpad(initcap(trim(ename)),10,' ') name, job, sal from emp
*
第 1 行出现错误:
ORA-00942: 表或视图不存在
SQL> 从 Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Produc
tion
With the Partitioning, OLAP, Data Mining and Real Application Testing options 断
开
C:\Users\yuehui>
C:\Users\yuehui>
C:\Users\yuehui>