php mysql select 日期从 1 天前到分钟

Question

I want to capture data that took place at the same hour and minute 24 hours ago. the formula below does not work. what could be the truth? I will draw the date range in a single line, not listing.

$now=time();
$24hrb=$now-(24*60*60);
$que = $connc->query("select * from table where datetime='$24hrb';")

Answer 1

In my opinion it would be best to do this all in SQL. You can use the mysql interval s options to reduce by 1 day then like and substr to trim the seconds off and only pull the datetime through the minute value.

select * from table where datetime like concat(substr((now() - interval 1 day), 1, 16), '%')

The substr is taking from a string like this:

2021/01/22 11:12:21
^              ^

and concat throws the wildcard on the end so anything after that matches. So your like is processed as:

2021/01/22 11:12%

Answer 2

$24hrb=time() - (24*60*60);

This is a Timestamp value. But you state in comments:

yes. datetime format Ymd H:i:s

So what you actually should be doing if you insist on using this method is converting your datetime to a Unix timestamp :

$que = $connc->query("SELECT * FROM table 
       WHERE UNIX_TIMESTAMP(`datetime_column`) = '".(int)$24hrb."'");

This is much better and easier to read than messing around with concatenations and string manipulations.

Further,

You can extend this action using the MySQL BETWEEN keyword so that you can get the values found between the range of times, say +/- 30 seconds. so:

$que = $connc->query("SELECT * FROM table 
       WHERE UNIX_TIMESTAMP(`datetime_column`) 
       BETWEEN ".($24hrb - 30)." AND ".($24hrb + 30));