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oracle的substr函数的用法

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

 

oracle的substr函数的用法