每天从日期中选择mysql数据

I've a table in HTML whichs looks like this:

[Day Before Yesterday] [Yesterday] [Today]

Now I want to spit out the amount of transactions that day, but how day I do that with a query? I've saved the transactions date in unix timestamp, so I was thinking about doing a query like this for today:

$today = time();

   $yesterday = $today - 86400;

   //Query for getting today amount of purchases

   $query = "SELECT * FROM purchases WHERE date > $yesterday";

   $result = mysqli_query($con,$query);

   $todayamount = mysqli_num_rows($result);

And I think that works fine for today results, but how do I do it for yesterday, that it won't select the the results from today etc? Please help me, because my ideas aren't working..

Use BETWEEN to get transactions from a particular day.

$two_days_ago = $today - 86400*2;
$query = "SELECT * FROM purchases WHERE date BETWEEN $two_days_ago AND $yesterday";

You can also do the calculations in MySQL:

$query = "SELECT * FROM purchases 
          WHERE date BETWEEN UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 2 DAY)) AND UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 DAY))";