SELECT DAYOFWEEK('2015-08-14'); -- 范围1-7,周日=1
SELECT DAYOFYEAR('2015-08-14');
SELECT DAYOFMONTH('2015-08-14');
SELECT DAY('2015-08-14');
SELECT DATE_FORMAT('2015-08-01 12:46:11','%H%i%S') a,DATE_FORMAT('2015-08-01 12:46:11','%H:%i:%S') b,DATE_FORMAT('2015-08-01 12:46:11','%H-%i-%S') c,DATE_FORMAT(NOW(),'%H:%i:%S') d;
SELECT DATE_FORMAT('2015-08-01 12:46:11','%H') a,DATE_FORMAT('2015-08-01 12:46:11','%H') b,DATE_FORMAT('2015-08-01 12:46:11','%H') c,DATE_FORMAT(NOW(),'%H') d;
SELECT SUBSTRING('2015-08-01 12:46:11',12,8);
SELECT DATE_FORMAT('2015-08-01 12:46:11','%H');
SELECT WEEKDAY('2015-08-14'); -- 对应工作日的索引 ，范围0-6， 周一 = 0
SELECT WEEKDAY(NOW());
SELECT YEAR(NOW());
SELECT MONTH(NOW());
SELECT QUARTER(NOW()); -- 第几个季度
SELECT HOUR(NOW());
SELECT MINUTE(NOW());
SELECT SECOND(NOW());
SELECT TO_DAYS(NOW());
SELECT TO_DAYS('2016-02-07')-TO_DAYS(NOW()); -- 计算当前时间到过年还有多少天
SELECT FROM_DAYS(700000);
SELECT CURDATE(); -- 当前日期
SELECT CURDATE()+0; -- 当前日期
SELECT CURTIME(); -- 当前日期
SELECT CURTIME()+0; -- 当前日期
SELECT NOW();
SELECT NOW()+0;