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在 Oracle 中使用正则表达式

作者: killkill  来源: 博客园  发布时间: 2010-09-07 11:24  阅读: 1548 次  推荐: 1   原文链接   [收藏]  

Oracle使用正则表达式离不开这4个函数:

1。regexp_like

2。regexp_substr

3。regexp_instr

4。regexp_replace

看函数名称大概就能猜到有什么用了。

 

regexp_like 只能用于条件表达式,和 like 类似,但是使用的正则表达式进行匹配,语法很简单:

regexp_substr 函数,和 substr 类似,用于拾取合符正则表达式描述的字符子串,语法如下:


regexp_instr 函数,和 instr 类似,用于标定符合正则表达式的字符子串的开始位置,语法如下:

regexp_replace 函数,和 replace 类似,用于替换符合正则表达式的字符串,语法如下:


这里解析一下几个参数的含义:

1。source_char,输入的字符串,可以是列名或者字符串常量、变量。

2。pattern,正则表达式。

3。match_parameter,匹配选项。

        取值范围: i:大小写不敏感; c:大小写敏感;n:点号 . 不匹配换行符号;m:多行模式;x:扩展模式,忽略正则表达式中的空白字符。

4。position,标识从第几个字符开始正则表达式匹配。

5。occurrence,标识第几个匹配组。

6。replace_string,替换的字符串。

 

说了一堆文绉绉的,现在开始实例演练了,在此之前先建好一个表。

create table tmp as 
with data as (
  select 'like' as id ,'a9999' as str from dual union all
  select 'like'       ,'a9c'          from dual union all
  select 'like'       ,'A7007'        from dual union all
  select 'like'       ,'123a34cc'     from dual union all 
  select 'substr'     ,'123,234,345'  from dual union all
  select 'substr'     ,'12,34.56:78'  from dual union all
  select 'substr'     ,'123456789'    from dual union all
  select 'instr'      ,'192.168.0.1'  from dual union all
  select 'replace'    ,'(020)12345678' from dual union all
  select 'replace'    ,'001517729C28' from dual  
)
select * from data ;

select * from tmp ;
ID      STR
------- -------------
like    a9999
like    a9c
like    A7007
like    123a34cc
substr  123,234,345
substr  12,34.56:78
substr  123456789
instr   192.168.0.1
replace (020)12345678
replace 001517729C28

 

regexp_like 例子:

select str from tmp where id='like' and regexp_like(str,'A\d+','i'); -- 'i' 忽略大小写
STR
-------------
a9999
a9c
A7007
123a34cc

select str from tmp where id='like' and regexp_like(str, 'a\d+');
STR
-------------
a9999
a9c
123a34cc

select str from tmp where id='like' and regexp_like(str,'^a\d+');
STR
-------------
a9999
a9c

select str from tmp where id='like' and regexp_like(str,'^a\d+$');
STR
-------------
a9999

 

regexp_substr 例子:

col str format a15;
select 
  str,
  regexp_substr(str,'[^,]+')     str,
  regexp_substr(str,'[^,]+',1,1) str,
  regexp_substr(str,'[^,]+',1,2) str,  -- occurrence 第几个匹配组
  regexp_substr(str,'[^,]+',2,1) str   -- position 从第几个字符开始匹配
from tmp
where id='substr';
STR             STR             STR             STR             STR
--------------- --------------- --------------- --------------- ---------------
123,234,345     123             123             234             23
12,34.56:78     12              12              34.56:78        2
123456789       123456789       123456789                       23456789

select 
  str, 
  regexp_substr(str,'\d')        str,
  regexp_substr(str,'\d+'  ,1,1) str,
  regexp_substr(str,'\d{2}',1,2) str,
  regexp_substr(str,'\d{3}',2,1) str 
from tmp      
where id='substr';
STR             STR             STR             STR             STR
--------------- --------------- --------------- --------------- ---------------
123,234,345     1               123             23              234
12,34.56:78     1               12              34
123456789       1               123456789       34              234


select regexp_substr('123456789','\d',1,level) str  --取出每位数字,有时这也是行转列的方式
from dual
connect by level<=9
STR
---------------
1
2
3
4
5
6
7
8
9

 

regex_instr 例子:

col ind format 9999;
select
  str, 
  regexp_instr(str,'\.'    ) ind ,
  regexp_instr(str,'\.',1,2) ind ,
  regexp_instr(str,'\.',5,2) ind
from tmp where id='instr';
STR               IND   IND   IND
--------------- ----- ----- -----
192.168.0.1         4     8    10
    
select 
  regexp_instr('192.168.0.1','\.',1,level) ind ,  -- 点号. 所在的位置
  regexp_instr('192.168.0.1','\d',1,level) ind    -- 每个数字的位置
from dual 
connect by level <=  9
  IND   IND
----- -----
    4     1
    8     2
   10     3
    0     5
    0     6
    0     7
    0     9
    0    11
    0     0

 

regex_replace 例子:

select 
  str,
  regexp_replace(str,'020','GZ') str,
  regexp_replace(str,'(\d{3})(\d{3})','<\2\1>') str -- 将第一、第二捕获组交换位置,用尖括号标识出来
from tmp
where id='replace';  
STR             STR             STR
--------------- --------------- ---------------
(020)12345678   (GZ)12345678    (020)<456123>78
001517729C28    001517729C28    <517001>729C28

 

综合应用的例子:

col row_line format a30;
with sudoku as (
  select '020000080568179234090000010030040050040205090070080040050000060289634175010000020' as line
  from dual
),
tmp as (
  select regexp_substr(line,'\d{9}',1,level) row_line,
  level col
  from sudoku
  connect by level<=9
)
select regexp_replace( row_line ,'(\d)(\d)(\d)(\d)(\d)(\d)(\d)(\d)(\d)','\1 \2 \3 \4 \5 \6 \7 \8 \9') row_line
from tmp

ROW_LINE
------------------------------
0 2 0 0 0 0 0 8 0
5 6 8 1 7 9 2 3 4
0 9 0 0 0 0 0 1 0
0 3 0 0 4 0 0 5 0
0 4 0 2 0 5 0 9 0
0 7 0 0 8 0 0 4 0
0 5 0 0 0 0 0 6 0
2 8 9 6 3 4 1 7 5
0 1 0 0 0 0 0 2 0
1
0

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