SELECT * FROM table WHERE <timestamp-field> BETWEEN 'YYYY-MM-DD 00:00:00' AND 'YYYY-MM-DD 23:59:59'

尽可能避免在现场进行计算：例如

Allways avoid doing calculations on the field if possible: e.g.

SELECT * FROM table WHERE DATE(<timestamp-field>) = 'YYYY-MM-DD'

将计算所有行的DATE那个桌子，所以你真的在说浪费这个循环吧

will calculate DATE() for ALL rows in that table, so you are really talking wasted cycles here