我有一个数据库表，看起来像这样：
uid | group | category
1 | group1 | cat1
2 | group1 | cat2
3 | group2 | cat3
4 | group2 | cat4
5 | group2 | cat5
6 | group3 | cat6
7 | group3 | cat7
但是我需要在数组中按类别将数据分组的数据group。
例如，我的数组应如下所示：
Array
(
[group1] => Array
(
[0] => Array
(
[0] => 1
[1] => cat1
)
[1] => Array
(
[0] => 2
[1] => cat2
)
)
[group2] => Array
(
[0] => Array
(
[0] => 3
[1] => cat3
)
[1] => Array
(
[0] => 4
[1] => cat4
)
[2] => Array
(
[0] => 5
[1] => cat5
)
)
[group3] => Array
(
[0] => Array
(
[0] => 6
[1] => cat6
)
[1] => Array
(
[0] => 7
[1] => cat7
)
)
)
我已经编写了一个foreach循环来执行此操作，但是有一个问题。
我的问题是，它总是遗漏了表格的最后一行，而且我不确定如何解决它。在我看来，逻辑指示它应该始终有效。
我以为在循环之后，我可以只将最后一行添加到新数组中，但是我认为如果最后一行具有不同的组，则可能会导致问题，我宁愿将解决方案内置到foreach循环中。
不幸的是，我在这里茫然。如何修复代码以包括数据库查询的最后一行？
我也很想知道我可以对当前代码进行哪些改进，但这对于codereview可能是一个更好的问题。
我的循环：
$pass = [];
foreach($stmt as $key => $value) {
if(empty($currentGroup)) $currentGroup = $value['group'];
if(empty($temp)) $temp = [];
if($currentGroup != $value['group'] || $key+1 == count($stmt)) {
$pass[$currentGroup] = $temp;
$currentGroup = $value['group'];
$temp = [];
$temp[] = [$stmt[$key]['uid'], $stmt[$key]['category']];
} else {
$temp[] = [$stmt[$key]['uid'], $stmt[$key]['category']];
}
}
请执行以下操作：
<?php
//Create an array to store our grouped rows
$grouped = array();
//Loop over all rows returned by the $stmt that has been executed.
//You could probably remove the key from here, it's not needed it seems.
//The keys within the $value array will match the names of the columns in
//the database,
foreach($stmt as $key => $value){
//As we're storing by the group value from the row we first want to
//check if our grouped array contains a key for the group of the row
//being processed. If it does not, create an empty array within the
//grouped data for this group.
if(!array_key_exists($value['group'], $grouped)){
$grouped[$value['group']] = array();
}
//Knowing we will always have an array element for the rows group
//we can blindly append the values for this row to the grouped
//container using its values.
//'[] =' is just short hand append.
$grouped[$value['group']][] = array(
$value['uid'],
$value['category']
);
}
希望有帮助！
为了进一步证明此循环，您可以更改以下分组值：
<?php
//Setting the whole row (minus the group) rather than just the uid
//and category explicitly allows this code to work without modification
//as the datatable changes, ie. new columns. Assuming that is the 'group'
//column remains present
unset($value['group']);
$grouped[$value['group']][] = $value;
现在可以使用以下命令访问已分组的内容数据：
<?php
//Acceess data via column name not array index, yay!
echo $grouped['group1']['uid']
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