CASE WHEN ceil(months_between(sysdate, BIRTHDAY)) <![CDATA[ < ]]> 12
THEN CONCAT(ceil(months_between(sysdate, BIRTHDAY)), '月')
ELSE CONCAT(ceil(months_between(sysdate, BIRTHDAY)/12), '岁')
END AS age
判断当前日期减出生日期是否小于12个月，小于--返回几个月，不小于--将月份除以12返回几岁
months_between返回月份
ceil返回大于或等于的值
例子: select months_between(sysdate, to_date('2018-12-13', 'yyyy-mm-dd')) from dual
