日期/时间操做符下表演示了基本算术操作符的行为(+,-,*,/等)：类型1操作符类型2返回类型示例、说明DATE-DATEINTERVAL DAY TO DAYdate('2020-05-08') - date('2020-05-01') 值为7DATE-DATETIMEINTERVAL DAY TO DAYdate('2020-05-08') - datetime(2020-05-01 12:00:00) year to second 值为7DATE+ -INTERVAL DAY TO DAYDATETIMEdate('2020-05-08') + interval(10) day to day 值为2020-05-18 00:00:00DATE+ -NUMBERDATEdate('2020-05-08') - 10 值为2020-04-28DATETIME-DATEINTERVALcurrent year to second - date('2020-05-08')值为 0 20:46:57当前时间为2020-05-08 20:46:57，将DATE类型转换为当天00:00:00DATETIME-DATETIMEINTERVALcurrent year to second - datetime(2020-05-01 12:58:58) year to second 值为 7 07:50:05DATETIME+ -INTERVALDATETIMEcurrent year to second - interval(03:04:05) hour to second 值为2020-05-08 17:46:02DATETIME+ -NUMBERDATETIMEcurrent year to second + 2/24/60 值为2020-05-08 21:07:17当前时间为2020-05-08 21:05:17，2/24/60 (2分钟)INTERVAL+ -INTERVALINTERVALinterval(03:04:05) hour to second + interval(3) hour to hour 值为 6:04:05INTERVAL* /NUMBERINTERVALinterval(03:04:05) hour to second * 4 值为12:16:20[...]