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