数据库结果的重复数据删除数组

Question

来自 PDO 查询的结果集如下...

Array
(
[0] => Array
    (
        [activity_link_type] => Category
        [data_id] => 1
    )

[1] => Array
    (
        [activity_link_type] => Category
        [data_id] => 38
    )

[2] => Array
    (
        [activity_link_type] => PData
        [data_id] => 108
    )

[3] => Array
    (
        [activity_link_type] => PData
        [data_id] => 109
    )

[4] => Array
    (
        [activity_link_type] => PData
        [data_id] => 112
    )

[5] => Array
    (
        [activity_link_type] => PData
        [data_id] => 115
    )

[6] => Array
    (
        [activity_link_type] => Role
        [data_id] => 6
    )
)

我希望以最简单的方式对数组进行“重复数据删除”（无需执行多个嵌套数据库查询），因此它看起来像以下...

Array
(
[0] => Array
    (
        [activity_link_type] => Category
        [data_id] => 1
        [data_id] => 38
    )

[1] => Array
    (
        [activity_link_type] => PData
        [data_id] => 108
        [data_id] => 109
        [data_id] => 112
        [data_id] => 115
   
[2] => Array
    (
        [activity_link_type] => Role
        [data_id] => 6
    )
)

我尝试过array_merge()、array_merge_recursive和array_unique()，但它们要么什么都不做，要么对数组的错误级别进行重复数据删除！

感谢所有帮助！

Answer 1

你认为你想要的数组是不可能的，但是这个怎么样，它相当接近并且还产生一个以activity_link_type作为键的数组，实际上在以后尝试访问这个数组时可能很有用

$from_db = [
            ['activity_link_type' => 'Category', 'data_id' => 1 ],
            ['activity_link_type' => 'Category', 'data_id' => 38 ],
            ['activity_link_type' => 'PData', 'data_id' => 108 ],
            ['activity_link_type' => 'PData', 'data_id' => 112 ],
            ['activity_link_type' => 'PData', 'data_id' => 115 ],
            ['activity_link_type' => 'Role', 'data_id' => 6 ]
];

$new = [];

foreach ( $from_db as $a){
    if ( isset( $new[$a['activity_link_type']] ) ) {
        $new[$a['activity_link_type']]['data_ids'][] = $a['data_id'];
    } else {
        $new[$a['activity_link_type']] = ['activity_link_type' => $a['activity_link_type'], 
                                          'data_ids' => [$a['data_id']] ];
    }   
}
print_r($new);

结果

Array
(
    [Category] => Array
        (
            [activity_link_type] => Category
            [data_ids] => Array
                (
                    [0] => 1
                    [1] => 38
                )
        )
    [PData] => Array
        (
            [activity_link_type] => PData
            [data_ids] => Array
                (
                    [0] => 108
                    [1] => 112
                    [2] => 115
                )
        )
    [Role] => Array
        (
            [activity_link_type] => Role
            [data_ids] => Array
                (
                    [0] => 6
                )
        )
)