如何在PHP foreach循环中对数据库中的记录进行分组，然后将值合并到一个新数组中？

Question

I have a table in a MySQL database that is used to store games that someone can book on. The games can be held in more than one location but they can also share the same time as another game. Here is an example of the data in the array that is taken from the MySQL database:

[0] => Array
    (
        [id] => 174
        [gamedatetime] => DateTime Object
            (
                [date] => 2016-02-08 14:00:00.000000
                [timezone_type] => 3
                [timezone] => Europe/London
            )

        [available] => 1
        [gameID] => 1
        [isBooked] => 
    )

[1] => Array
    (
        [id] => 175
        [gamedatetime] => DateTime Object
            (
                [date] => 2016-02-08 14:00:00.000000
                [timezone_type] => 3
                [timezone] => Europe/London
            )

        [available] => 1
        [gameID] => 1
        [isBooked] => 1
    )

[2] => Array
    (
        [id] => 176
        [gamedatetime] => DateTime Object
            (
                [date] => 2016-02-08 15:00:00.000000
                [timezone_type] => 3
                [timezone] => Europe/London
            )

        [available] => 1
        [gameID] => 1
        [isBooked] => 
    )

What I need to do is create an array with this data on it, but grouped by the date and time, and the gameID are joined together but comma separated, like this:

[0] => Array
    (
        [gamedatetime] => 2016-02-08 14:00:00.000000
        [id] => 174,175
    )
[1] => Array
    (
        [gamedatetime] => 2016-02-08 15:00:00.000000
        [id] => 176
    )

How can I achieve this using PHP?

Answer 1

The following will achieve what you are aiming for but the ids will be in a subarray, allowing you to concatenate together as you need them.

$newArray = [];
foreach ($oldArray as $game) {
    $newArray[$game['gamedatetime']]['gamedatetime'] = $game['gamedatetime'];
    $newArray[$game['gamedatetime']]['ids'][] = $game['id'];
}

or you can change the query to something like:

SELECT gamedatetime, GROUP_CONCAT(id) as `id`
FROM game
WHERE ...
GROUP BY gamedatetime