• [原]在 Oracle 中使用正则表达式


    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_like_condition

    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_substr 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_instr

    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:

    regexp_replace

    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
    
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  • 原文地址:https://www.cnblogs.com/killkill/p/1819536.html
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