Question

我有一个这种格式的表

id1 | id2 | id3 | id4  | id5
a   | b   | c   | null | null
a   | b   | d   | null | null
a   | b   |null | null | null

我需要得到结果(a,b,c,d)

我用php制作，但代码太难了......

    <?php
    $sql="SELECT t1.id as id1, t2.id AS id2, t3.id AS id3, t4.id AS id4, t5.id AS id5
    FROM store_subcategory AS t1
    LEFT JOIN store_subcategory AS t2 ON t2.parent_id = t1.id
    LEFT JOIN store_subcategory AS t3 ON t3.parent_id = t2.id
    LEFT JOIN store_subcategory AS t4 ON t4.parent_id = t3.id
    LEFT JOIN store_subcategory AS t5 ON t5.parent_id = t4.id
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id";

    $result=$mysqli->query($sql);
    $subid=array();
    while($row=$result->fetch_assoc())
    {
        if($row["id1"]!=null) $subid[$row["id1"]]=1;
        if($row["id2"]!=null) $subid[$row["id2"]]=1;
        if($row["id3"]!=null) $subid[$row["id3"]]=1;
        if($row["id4"]!=null) $subid[$row["id4"]]=1;
        if($row["id5"]!=null) $subid[$row["id5"]]=1;
    }
    $subsarray=array();
    foreach($subid as $key => $value)
    {
        array_push($subsarray, $key);
    }
    $subid=implode(",", $subsarray);
    ?>

由于 PS：抱歉我的英文不好

编辑：该表适用于具有5个级别的分层树

`store_subcategory` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `parent_id` int(11) DEFAULT NULL,
  `it` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)

EDIT2：解决方案可能是这个

SELECT * FROM (
SELECT DISTINCT(t1.id)
    FROM store_subcategory AS t1
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id
UNION
SELECT DISTINCT(t2.id)
    FROM store_subcategory AS t1
    LEFT JOIN store_subcategory AS t2 ON t2.parent_id = t1.id
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id
UNION
SELECT DISTINCT(t3.id)
    FROM store_subcategory AS t1
    LEFT JOIN store_subcategory AS t2 ON t2.parent_id = t1.id
    LEFT JOIN store_subcategory AS t3 ON t3.parent_id = t2.id
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id
UNION
SELECT DISTINCT(t4.id)
    FROM store_subcategory AS t1
    LEFT JOIN store_subcategory AS t2 ON t2.parent_id = t1.id
    LEFT JOIN store_subcategory AS t3 ON t3.parent_id = t2.id
    LEFT JOIN store_subcategory AS t4 ON t4.parent_id = t3.id
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id
UNION
SELECT DISTINCT(t5.id)
    FROM store_subcategory AS t1
    LEFT JOIN store_subcategory AS t2 ON t2.parent_id = t1.id
    LEFT JOIN store_subcategory AS t3 ON t3.parent_id = t2.id
    LEFT JOIN store_subcategory AS t4 ON t4.parent_id = t3.id
    LEFT JOIN store_subcategory AS t5 ON t5.parent_id = t4.id
    WHERE (t1.root_id=$cat or t1.id=$cat) and t1.store_id=$id
) AS t_group WHERE id IS NOT NULL

Answer 1

我不知道这个数据结构是如何有用的，但它听起来像你想要的东西：

SELECT DISTINCT(ID) 
FROM 
    (select distinct(id1) AS ID
    from table
    UNION
    select distinct(id2) AS ID
    from table
    UNION
    select distinct(id3) AS ID
    from table)

MySQL - 将表结果转换为行

1 个答案: