The first method: cross join (equivalent circulating in mysql)
CROSS JOIN two data tables will be a combination of N * M, i.e., Cartesian product
After this two tables use five data union all have, so there were 25 cross join data
Interval designated date will be generated from the data bus 25
select CURDATE() - INTERVAL '1' day
NOW () (to get the current date and time) CURDATE () (to get the current date) CURTIME () (to get the current time)
INTERVAL used herein is a function of variables which can be used to replace the constant
specific reference https://blog.csdn.net/sqlquan/article/details/82699237
Add between and you can get a specified date and time