PHP高效的取出所有下级：
递归取出所有下级：
1,
'username' => '155',
'parent_username' => '0'
],
[
'uid' => 2,
'username' => '186',
'parent_username' => '155'
],
[
'uid' => 3,
'username' => '189',
'parent_username' => '186'
],
[
'uid' => 4,
'username' => '188',
'parent_username' => '155'
],
[
'uid' => 5,
'username' => '187',
'parent_username' => '188'
],
[
'uid' => 6,
'username' => '1898',
'parent_username' => '146'
],
];
/**
* 获取所有下级
* [getTree description]
* @param [type] $data [description]
* @param string $parent_username [description]
* @return [type] [description]
*/
//有层次，返回所有下级数据
function getTree($data, $parent_username = '0')
{
$arr = [];
foreach($data as $key => $val){
if($val['parent_username'] == $parent_username){
$val['children'] = getTree($data, $val['username']);
$arr[] = $val;
}
}
return $arr;
}
//无层次，仅返回id
function getTree($data, $parent_username = '0', $is_first_time = true)
{
static $arr = [];
if ($is_first_time) {
$arr = [];
}
foreach ($data as $key => $val) {
if ($val['parent_username'] == $parent_username) {
$arr[] = $val['uid'];
getTree($data, $val['username'], false);
}
}
return $arr;
}
echo '';
print_r(getTree($data));
?>
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