ELT(N,str1,str2,str3,...)
如果N =1返回str1,如果N= 2返回str2,等等。返回NULL如果参数的数量小于1或大于N。ELT()是FIELD()的补集。
mysql> SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo'); +---------------------------------------------------------+ | ELT(1, 'ej', 'Heja', 'hej', 'foo') | +---------------------------------------------------------+ | ej | +---------------------------------------------------------+ 1 row in set (0.00 sec)