oracle的substr函数的用法

Posted 2020-08-19 美好的明天

取得字符串中指定起始位置和长度的字符串   substr( string, start_position, [ length ] )
 如:

     substr(\'This is a test\', 6, 2)     would return \'is\'
     substr(\'This is a test\', 6)     would return \'is a test\'
     substr(\'TechOnTheNet\', -3, 3)     would return \'Net\'
     substr(\'TechOnTheNet\', -6, 3)     would return \'The\'

  select substr(\'Thisisatest\', -4, 2) value from dual    结果是   te

select substr(\'emros\',-3,1) value from dual      结果是 r

 

substr(\'abcde\',-6) = null 
substr(\'abcde\',-5) = \'abcde\' 
substr(\'abcde\',-4) = \'bcde\' 
substr(\'abcde\',-3) = \'cde\' 
substr(\'abcde\',-2) = \'de\' 
substr(\'abcde\',-1) = \'e\' 
substr(\'abcde\',-0) = \'abcde\'