如何在PHP MySQL JOIN結果上進行分組？

Question

預期結果：

Berries: blueberry, raspberry, strawberry 
Citrus: grapefruit, lime 
Pear 

---

SQL：

CREATE TABLE IF NOT EXISTS `fruits` (
    `id` varchar(8) NOT NULL, 
    `group` varchar(8) NOT NULL, 
    `name` varchar(250) NOT NULL, 
    PRIMARY KEY (`id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8; 

INSERT INTO `fruits` (`id`, `group`, `name`) VALUES 
('03E7', '', 'Berries'), 
('0618', '03E7', 'blueberry'), 
('051B', '03E7', 'raspberry'), 
('02AA', '03E7', 'strawberry'), 
('035F', '', 'Citrus'), 
('07A5', '035F', 'grapefruit'), 
('0633', '035F', 'lime'), 
('05E1', '', 'Pear'); 

當前PHP：

<?php 

header("Content-Type: text/plain"); 

mysql_connect("localhost", "root", ""); 
mysql_select_db("test"); 

$query = mysql_query("SELECT a.name as `group`, b.name as name FROM fruits a LEFT JOIN fruits b ON b.`group` = a.id WHERE a.`group` = ''"); 

if ($query) { 
    while ($row = mysql_fetch_array($query)) { 
     echo $row['group'] . ': ' . $row['name'] . "\n";   
    } 
    mysql_free_result($query); 
} 

?> 

當前結果：

Berries: blueberry 
Berries: raspberry 
Berries: strawberry 
Citrus: grapefruit 
Citrus: lime 
Pear: 

Answer 1

感謝@ExplosionPills發現我關於MySQL GROUP_CONCAT我已經更新了我的代碼片段：

<?php 

$query = mysql_query("SELECT a.name as `group`, GROUP_CONCAT(b.name ORDER BY b.name SEPARATOR ', ') as name FROM fruits a LEFT JOIN fruits b ON b.`group` = a.id WHERE a.`group` = '' GROUP BY a.name"); 

if ($query) { 
    while ($row = mysql_fetch_array($query)) { 
     $group = $row['group']; 
     $name = $row['name']; 

     if (isset($name)) { 
      echo $group . ': ' . $name . "\n"; 
     } else { 
      echo $group . "\n"; 
     } 
    } 
    mysql_free_result($query); 
} 

?> 

SQL結果：

顯示行0 - 2（3總計，查詢花費0.0004秒）。

group | name 
--------+-------- 
Berries | blueberry, raspberry, strawberry 
Citrus | grapefruit, lime 
Pear | NULL 

PHP結果：

Berries: blueberry, raspberry, strawberry 
Citrus: grapefruit, lime 
Pear 

每個人都歡迎任何有更好的改善更好地實施？

Answer 2

SELECT a.name, GROUP_CONCAT(b.name) ... WHERE a.group = '' GROUP BY a.name 

總之，你需要一個GROUP BY條款，並且分組的列需要以某種方式彙總（否則你將得到只有一個值）。如果這不起作用，你可以很容易地做到這一點在與你得到的結果PHP代碼：返回預期的結果

$fruits = array(); 
while ($row = fetch($query)) { 
    //Can be skipped, but you will get notices 
    if (!isset($fruits[$row['group']]) { 
     $fruits[$row['group']] = array(); 
    } 
    $fruits[$row['group']] = $row['name']; 
}