oracle的substr函數的用法

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取得字串中指定起始位置和長度的字串   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    結果是   teselect substr(‘emros‘,-3,1) value from dual      結果是 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函數的用法