MySQL SQL min（）和max（）查询数组回显零

Question

I have a table set up with 5 columns:

user_id, 5k, 10k, halfmarathon, and marathon.

I want to display the user's best times on a user page for each distance of run. The user will be able to update any of the times which creates a new row and the rest of the columns are set to null. So for example,

Row 1 is:

user_id: 5, 5k: null, 10k: 45:00, half: null, marathon: null.

Then the user runs another 10k and gets a better time, plus wants to update their 5k time :

Row 2 is then:

user_id: 5, 5k: 15:53, 10k: 40:40, half: null, marathon: null.

When I run the following SQL query

$query = "SELECT MIN(5k), MIN(10k), MIN(halfmartahon), MIN(marathon)
        FROM Times
        WHERE user_id = ".$userID."
        GROUP BY user_id";
$db->query($query);
//Assign Result Set
$user_benchmarks = $db->single();`

I get an array that is correct when I vardump() (I am storing the times in seconds) :

object(stdClass)#18 (4) { ["MIN(5k)"]=> string(3) "953" ["MIN(10k)"]=> string(4) "2440" ["MIN(halfmarathon)"]=> string(1) "0" ["MIN(marathon)"]=> string(1) "0" }

However, when I try to echo this, so $user_benchmarks->5k it doesn't show anything and when I run print_r($user_benchmarks->5k) it comes back as NULL .

Has anyone encountered this / know what's happening? I've also tried turning the string to an integer before printing it to no avail - still get NULL .

Answer 1

var_dump already showed you exactly what keys to use:

object(stdClass)#18 (4) { ["MIN(5k)"]=> string(3) "953"
                            ^^^^^^^

so why are you using

$user_benchmarks->5k
                 ^^^

?

Answer 2

It's because the "5k" property of the $user_benchmarks object doesn't exist. You need to access the "MIN(5k)" property instead. So for example:

echo $user_benchmarks->{"MIN(5k)"};

On the other hand you can change the query to something like this:

SELECT MIN(5k) AS `5k`, MIN(10k) AS `10k` ...

Then you will be able to access properties "5k" and "10k" just like you wanted.

Answer 3

Use

SELECT MIN(5k) as 5k, 
       MIN(10k) as 10k, 
       MIN(halfmartahon) as halfmartahon, 
       MIN(marathon) as marathon