学习的时候我喜欢对比，MySQL和Oracle比，Python和MySQL比，总能有一些收获，也有了新的理解。

今天整理这部分内容的时候，我发现Python和MySQL还是有很多相似之处。学习一门语言，一个数据库，字符串的处理都是一个相对重要的部分，所以我决定对比一下两者的差别。

下面的演示会一边Python,一边MySQL,所以按照这个思路来看就不会感觉突兀了。

转义字符

>>> print '\\'

\ mysql> select '\\'; +---+ | \ | +---+ | \ | +---+ >>> print '\"' " mysql> select '\"'; +---+ | " | +---+ | " | +---+ >>> print '\'' ' mysql> select '\''; +---+ | ' | +---+ | ' | +---+

字符串拼接

>>> x = 'hello' >>> y = 'tester' >>> z = x + y >>> print z hellotester set @x='hello'; set @y='tester'; mysql> select @x; +-------+ | @x    | +-------+ | hello | mysql> select @y; +--------+ | @y     | +--------+ | tester | +--------+ mysql> select concat(@x,@y); +---------------+ | concat(@x,@y) | +---------------+ | hellotester   | +---------------+

字符串复制

>>> print '#'*20 #################### mysql> select repeat('#',20); +----------------------+ | repeat('#',20)       | +----------------------+ | #################### | +----------------------+ >>> print ' '*20 + 'end'                     end mysql> select space(20); +----------------------+ | space(20)            | +----------------------+ |                      | +----------------------+                     

字符串截取

>>> name = 'yangjianrong' >>> name[0] 'y' >>> name[-1] 'g' >>> name[1] 'a' >>> name[1:4] 'ang' >>> name[:] 'yangjianrong' >>> >>> name[1:4:2] 'ag' mysql> set @name:='yangjianrong'; mysql> select left(@name,1);          +---------------+ | left(@name,1) | +---------------+ | y             | +---------------+ mysql> select right(@name,1); +----------------+ | right(@name,1) | +----------------+ | g              | +----------------+ mysql> select substring(@name,2,3); +----------------------+ | substring(@name,2,3) | +----------------------+ | ang                  | +----------------------+ mysql> select substring(@name,1); +--------------------+ | substring(@name,1) | +--------------------+ | yangjianrong       | +--------------------+ 或者使用mid mysql> select mid(@name,2,3);          +----------------+ | mid(@name,2,3) | +----------------+ | ang            | +----------------+ mysql>  select mid(@name,1);          +--------------+ | mid(@name,1) | +--------------+ | yangjianrong | +--------------+ >>> name 'yangjianrong' >>> print '%s' %name yangjianrong

字符串格式化，匹配

>>> '{name},{alias}'.format(name='yangjianrong',alias='jeanron100')     'yangjianrong,jeanron100' >>> mysql>  select concat(insert(@name,1,4,'yangjianrong'),insert(@alias,1,5,'jeanron100')) comm; +------------------------+ | comm                   | +------------------------+ | yangjianrongjeanron100 | +------------------------+ 字符串长度>>> ba 'this is a test bar' >>> len(ba) 18 mysql> select length(@ba);

字符串空格处理

>>> s = ' abc '

>>> s.lstrip() 'abc ' >>> s.rstrip() ' abc' >>> s.strip() 'abc' >>> mysql> set @s=' abc '; Query OK, 0 rows affected (0.00 sec) mysql> select ltrim(@s); +-----------+ | ltrim(@s) | +-----------+ | abc       | +-----------+ 1 row in set (0.00 sec) mysql> select rtrim(@s); +-----------+ | rtrim(@s) | +-----------+ |  abc      | +-----------+ 1 row in set (0.00 sec) mysql> select trim(@s); +----------+ | trim(@s) | +----------+ | abc      | +----------+ 1 row in set (0.00 sec) 字符串匹配 >>> l = ['a','b','c'] >>> ''.join(l) 'abc' >>> '*'.join(l) 'a*b*c' mysql> select concat_ws(',','a','b','c','d','e') comm; +-----------+ | comm      | +-----------+ | a,b,c,d,e | +-----------+ >>> s = 'a b c d e ' >>> s.split(' ') ['a', 'b', 'c', 'd', 'e', ''] mysql> set @s='a b c d e '; Query OK, 0 rows affected (0.00 sec) mysql> select replace(@s,' ',','); +---------------------+ | replace(@s,' ',',') | +---------------------+ | a,b,c,d,e,          | +---------------------+

字符串复制

>>> s = 'aabbcc' >>> s.replace('aa','tt') 'ttbbcc' mysql> set @s='aabbcc'; Query OK, 0 rows affected (0.00 sec) mysql> select replace(@s,'aa','tt'); +-----------------------+ | replace(@s,'aa','tt') | +-----------------------+ | ttbbcc                | +-----------------------+  字符串编码 >>> s.encode('utf8') 'aabbcc' mysql> select  convert(@s using utf8); +------------------------+ | convert(@s using utf8) | +------------------------+ | aabbcc                 | +------------------------+

判断字符串开始匹配的字符

>>> s.startswith('aa') True mysql> SELECT LOCATE('aa',@s,1);   +-------------------+ | LOCATE('aa',@s,1) | +-------------------+ |                 1 | +-------------------+

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