DATE_ADD(date,INTERVAL expr type)
eg:DATE_ADD(CURDATE(),INTERVAL 1 MONTH) //在当前时间加一个月

eg:select birth ,CURDATE, YEAR(CURDATE())-YEAR(birth) - (RIGHT(MONTH(CURDATE)，５) < ＲIGHT(MONTH(birth),5)) as age from pet;

birth                  CURDATE         age

1998-09-11       2003-08-19      4

YEAR() 获取年，MONTH() 获取月,day() 获取天

eg:SELECT article, dealer, price FROM  shop WHERE  price=(SELECT MAX(price) FROM shop);

eg:SELECT article, dealer, price FROM shop ORDER BY price DESC LIMIT 1;（假设有多个最大价格，那这个语句只能查找出一个）