1 $data = array(
2     '0' => array('id' => 10, 'username' => '陈一'),
3     '1' => array('id' => 11, 'username' => '洪二'),
4     '2' => array('id' => 12, 'username' => '张三'),
5     '3' => array('id' => 13, 'username' => '李四')
6 );

1 foreach ($data as $key=>$value) {
2     $idData[] = $value['id'];
3     $usernameData[] = $value['username'];
4 }
5
6 var_dump($idData);//array(4) { [0]=> int(10) [1]=> int(11) [2]=> int(12) [3]=> int(13) }
7 var_dump($usernameData);//array(4) { [0]=> string(6) "陈一" [1]=> string(6) "洪二" [2]=> string(6) "张三" [3]=> string(6) "李四" }

1 $callBackData = array_map(function($value){
2     return $usernameData[] = $value['username'];
3 }, $data);
4 var_dump($callBackData);//array(4) { [0]=> string(6) "陈一" [1]=> string(6) "洪二" [2]=> string(6) "张三" [3]=> string(6) "李四" }

1 $usernameData = array_column($data, 'username');
2 var_dump($usernameData);//array(4) { [0]=> string(6) "陈一" [1]=> string(6) "洪二" [2]=> string(6) "张三" [3]=> string(6) "李四" }

1 $usernameData = array();
2 array_walk($data, function($value, $key) use (&$usernameData){
3     $usernameData[] = $value['username'];
4 });
5 var_dump($usernameData);//array(4) { [0]=> string(6) "陈一" [1]=> string(6) "洪二" [2]=> string(6) "张三" [3]=> string(6) "李四" }

1 $usernameData = array_reduce($data,function(&$usernameData,$v){
2     $usernameData[] = $v['username'];
3     return $usernameData;
4 });
5 var_dump($usernameData);//array(4) { [0]=> string(6) "陈一" [1]=> string(6) "洪二" [2]=> string(6) "张三" [3]=> string(6) "李四" }