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>