Oracle 字串函式

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SQL> select greatest(111,222) from dual;

GREATEST(111,222)

-----------------

      222

SQL> select least(111,222) from dual;

LEAST(111,222)

--------------

   111

SQL> select floor(-7.8) from dual;

select sys_guid() from dual;

SYS_GUID()

--------------------------------

52E859DC8A9D0DA8E053FB6410AC9549

insert into t1 values('我們');

insert into t1 values('我你');

insert into t1 values('你們');

insert into t1 values('吃飯');

insert into t1 values('他');

> select * from t1 order by nlssort(name,'nls_sort=schinese_pinyin_m');

SQL> select systimestamp from dual;

SQL> select vsize(ename) "byte" from emp where deptno=30;

SQL> select ora_hash(ename) from emp;

SQL> select extract( hour from sysdate) year from emp;

SQL> select sign(3434) from dual;

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regular expression

regexp_count

regexp_instr

regexp_replace

regexp_substr

regexp_like

regexp_like

SQL> select ename from emp where regexp_like(ename,'A|S');

SQL> select ename from emp where ename like '%A%' or ename like '%S%';

SQL> select ename from emp where regexp_like(ename,'^A');

SQL> select ename from emp where regexp_like(ename,'G$');

SQL> select ename from emp where regexp_like(ename,'^[A-z]+$');

SQL> select ename from emp where regexp_like(ename,'s','c');

no rows selected

SQL> select ename from emp where regexp_like(ename,'S','i');

regexp_replace

selelect replace('abc','a','d')

 

select regexp_replace('abcabc','a','0',1,2,'i') from dual;

regexp_instr

SELECT REGEXP_INSTR('1234567890', '(123)(4(56)(78)0)', 1, 1, 1, 'i',1) 

"REGEXP_INSTR" FROM DUAL;

0123(((abc)(de)f)ghi)45(678)

abcdefghi  abcdef  abc  de 678

((河北省)(邢臺)(沙河))              

河北省邢臺啊啊

河北省邢臺版本

河北生石家莊

regexp_substr

select susbtr('172.16.50.1',)

172.16.100.1

172.168.9.

172.16.100.2

SELECT

  REGEXP_SUBSTR('500 Oracle Parkway, Redwood Shores, CA',

                ',[^,]+,') "REGEXPR_SUBSTR"

  FROM DUAL;

^[,]

[^,]

SELECT REGEXP_COUNT('123123123123', '123', 3, 'i') COUNT FROM DUAL;

DECODE

CASE 

10          +1000

20          +1500

30           x

40          -500

sign

sal 

<2000 

2000-4350  1%

4350+       2%

select 

decode  sal,sal<2000,sal,

   sal>=2000 and sal<4000, sal*0.99

case 

select 

case   when sal<2000 then sal

       when between 2000 and 4000  then sal*0.99

       else  sal*0.98

end   sal

from 

emp;

 

select 

case   when deptno =10  then sal+1000

       when deptno=20  then sal+2000

       else  sal

end   sal,

case   deptno  when 10  then sal+1000

               when 20  then sal+2000

       else  sal

end   sal,

from 

emp;

 

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最大值  最小值  平均值    求和  統計

max     min    avg      sum  count()

字元

數字

日期

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分組函式

select ...      group by 

  (1)  聚集函式

(2) 加到group by後面

select 

name,

sum(case subject when '語文' then grade else 0 end) "語文", 

max(case when subject='英語'  then grade else 0 end ) "英語", 

sum(decode(subject,'數學',grade,0)) "數學" 

from 

t4

group  by  name;

select '我們' from dual;