MYSQL选择这一天内的日期

Question

MY query looks like this:

SELECT COUNT(entryID) 
FROM table 
WHERE date >= DATE_SUB(CURDATE(), INTERVAL 1 DAY)

Will this count the rows whose date values are within the day (starting at 12:00; not within 24 hours)? If not, how do I do so?

Answer 1

The following should be enough to get records within the current day:

SELECT COUNT(entryID) 
FROM table 
WHERE date >= CURDATE()

As Michael notes in the comments, it looks at all records within the last two days in its current form.

The >= operator is only necessary if date is actually a datetime - if it's just a date type, = should suffice.

Answer 2

Here's the solution:

SELECT COUNT(entryID) FROM table WHERE DATE(date) >= CURDATE()

Since my date column is type DATETIME , I use DATE(date) to just get the date part, not the time part.

Answer 3

CURDATE() returns a date like '2012-03-30', not a timestamp like '2012-03-30 21:38:17'. The subtraction of one day also returns just a date, not a timestamp. If you want to think of a date as a timestamp think of it as the beginning of that day, meaning a time of '00:00:00'.

And this is the reason, why this

WHERE date >= DATE_SUB(CURDATE(), INTERVAL 1 DAY)

and this

WHERE date > CURDATE()

do the same.

I have another hint: SELECT COUNT(entryID) and SELECT COUNT(*) give the same result. SELECT COUNT(*) gives the database-machine more posibilities to optimize counting, so COUNT(*) is often (not always) faster than COUNT(field) .