Question

继承我的桌子：

Table: category
----------------
id | category 
------------------
1  |  category1 
2  |  category2
3  |  category3
4  |  category4
5  |  category5

-

Table: news
------------------------------
id | title      | category_id
------------------------------
 1 | title 1    |      1
 2 | title 2    |      2
 3 | title 3    |      4 
 4 | title 4    |      5
 5 | title 5    |      3
 6 | title 6    |      3
 7 | title 7    |      2
 8 | title 8    |      5
 9 | title 9    |      1
 10| title 10   |      4
 11| title 11   |      1
 12| title 12   |      2

如何获得 mysql结果，如下所示：

（注意：每个类别（1-5）仅分配一个标题，然后再次重复类别的循环。）

我尝试过按顺序使用`group by。

Category 1     ===
   title 1


 Category 2
   title

 Category 3
    title 5


Category 4
     title 3

Category 5
     title 4

Category 1     ===
     title 9

Category 2
     title 

category 3
      title 6

 category 4
       title10

 category 5
       title 8

 category 1      ===
       title 11

  category 2
        title 12

Answer 1

如果您想使用PHP构建此类格式，或者您可以使用while循环来创建它。考虑这个例子：

首先，您需要正确查询这些值，您可以使用join

// SAMPLE => SELECT * FROM `category` 
//    LEFT JOIN `news` ON `news`.`category_id` = `category`.`id`

示例输出：SQL HERE

其次，获取值后，您需要对它们进行排序，在这种情况下，(1, 2, 3, 4, 5)

考虑这个例子：

$results_from_db = array(
    array('id' => 1, 'category' => 'category1', 'title' => 'title 1', 'category_id' => 1),
    array('id' => 1, 'category' => 'category1', 'title' => 'title 9', 'category_id' => 1),
    array('id' => 1, 'category' => 'category1', 'title' => 'title 11', 'category_id' => 1),
    array('id' => 2, 'category' => 'category2', 'title' => 'title 2', 'category_id' => 2),
    array('id' => 2, 'category' => 'category2', 'title' => 'title 7', 'category_id' => 2),
    array('id' => 2, 'category' => 'category2', 'title' => 'title 12', 'category_id' => 2),
    array('id' => 3, 'category' => 'category3', 'title' => 'title 5', 'category_id' => 3),
    array('id' => 3, 'category' => 'category3', 'title' => 'title 6', 'category_id' => 3),
    array('id' => 4, 'category' => 'category4', 'title' => 'title 3', 'category_id' => 4),
    array('id' => 4, 'category' => 'category4', 'title' => 'title 10', 'category_id' => 4),
    array('id' => 5, 'category' => 'category5', 'title' => 'title 4', 'category_id' => 5),
    array('id' => 5, 'category' => 'category5', 'title' => 'title 8', 'category_id' => 5),
);


$ids = array();
foreach($results_from_db as $value) {$ids[] = $value['id'];}
$ids = array_values(array_unique($ids));
sort($ids);
$needle_key = 0;

// build the data (kinda like recursive searching)
$data = array();
while(true) {
    $current_value = array_shift($results_from_db);
    if($current_value['category_id'] == $ids[$needle_key]) {
        $data[] = $current_value;
        $needle_key++;
        if($needle_key > count($ids)-1) {
            $needle_key = 0; // resetter
        }
    } else {
        array_push($results_from_db, $current_value);
    }

    if(empty($results_from_db)) {
        break;
    }
}
?>

<!-- if you want to echo -- >
<?php foreach($data as $key => $value): ?>
    <?php echo '<strong>'.$value['category'].'</strong><br/>'; ?>
    <?php echo str_repeat('&nbsp;', 8) . $value['title'].'<br/><br/>'; ?>
<?php endforeach; ?>

应输出如下内容：Sample Fiddle

category1
        title 1

category2
        title 2

category3
        title 5

category4
        title 3

category5
        title 4

category1
        title 9

category2
        title 7

category3
        title 6

category4
        title 10

category5
        title 8

category1
        title 11

category2
        title 12

MySQL循环使用group by

1 个答案: