如何在多个列上分隔查询结果

时间：2018-05-20 04:20:20

标签： mysql

我有这张桌子

id  bigint(20) unsigned Incrément automatique    
form_id        mediumint(8)      unsigned [0]    
entry_id       bigint(20)        unsigned    
meta_key       varchar(255)      NULL    
meta_value     longtext          NULL

它显示如下数据：

<style type="text/css">
.tg  {border-collapse:collapse;border-spacing:0;}
.tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;}
.tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;}
.tg .tg-yw4l{vertical-align:top}
</style>
<table class="tg">
  <tr>
    <th class="tg-031e">id</th>
    <th class="tg-031e">form_id</th>
    <th class="tg-031e">entry_id</th>
    <th class="tg-yw4l">meta_key</th>
    <th class="tg-yw4l">meta_value</th>
  </tr>
  <tr>
    <td class="tg-031e">3</td>
    <td class="tg-031e">1</td>
    <td class="tg-031e">1</td>
    <td class="tg-yw4l">14</td>
    <td class="tg-yw4l">Address 1</td>
  </tr>
  <tr>
    <td class="tg-031e">6</td>
    <td class="tg-031e">1</td>
    <td class="tg-031e">1</td>
    <td class="tg-yw4l">20</td>
    <td class="tg-yw4l">1</td>
  </tr>
  <tr>
    <td class="tg-yw4l">7</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">21</td>
    <td class="tg-yw4l">2018-16-05</td>
  </tr>
  <tr>
    <td class="tg-yw4l">8</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">23</td>
    <td class="tg-yw4l">Product 1</td>
  </tr>
  <tr>
    <td class="tg-yw4l">11</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">14</td>
    <td class="tg-yw4l">Address 2</td>
  </tr>
  <tr>
    <td class="tg-yw4l">14</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">20</td>
    <td class="tg-yw4l">1</td>
  </tr>
  <tr>
    <td class="tg-yw4l">15</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">21</td>
    <td class="tg-yw4l">2018-16-05</td>
  </tr>
  <tr>
    <td class="tg-yw4l">16</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">2</td>
    <td class="tg-yw4l">23</td>
    <td class="tg-yw4l">Product2</td>
  </tr>
  <tr>
    <td class="tg-yw4l">20</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">14</td>
    <td class="tg-yw4l">Address3</td>
  </tr>
  <tr>
    <td class="tg-yw4l">21</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">20</td>
    <td class="tg-yw4l">1</td>
  </tr>
  <tr>
    <td class="tg-yw4l">22</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">21</td>
    <td class="tg-yw4l">2018-16-05</td>
  </tr>
  <tr>
    <td class="tg-yw4l">23</td>
    <td class="tg-yw4l">1</td>
    <td class="tg-yw4l">3</td>
    <td class="tg-yw4l">23</td>
    <td class="tg-yw4l">Prodcut3</td>
  </tr>
</table>

我需要的是使用选择请求：

<style type="text/css">
.tg  {border-collapse:collapse;border-spacing:0;}
.tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;}
.tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:10px 5px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;}
</style>
<table class="tg">
  <tr>
    <th class="tg-031e">meta_value1</th>
    <th class="tg-031e">meta_value2</th>
    <th class="tg-031e">meta_value3</th>
    <th class="tg-031e">meta_value4</th>
    <th class="tg-031e"></th>
  </tr>
  <tr>
    <td class="tg-031e">Address 1</td>
    <td class="tg-031e">1</td>
    <td class="tg-031e">2018-16-05</td>
    <td class="tg-031e">Product1</td>
    <td class="tg-031e"></td>
  </tr>
  <tr>
    <td class="tg-031e">Address 2</td>
    <td class="tg-031e">1</td>
    <td class="tg-031e">2018-16-05</td>
    <td class="tg-031e">Product2</td>
    <td class="tg-031e"></td>
  </tr>
  <tr>
    <td class="tg-031e">Address 3</td>
    <td class="tg-031e">1</td>
    <td class="tg-031e">2018-16-05</td>
    <td class="tg-031e">Prodcut3</td>
    <td class="tg-031e"></td>
  </tr>
  <tr>
    <td class="tg-031e"></td>
    <td class="tg-031e"></td>
    <td class="tg-031e"></td>
    <td class="tg-031e"></td>
    <td class="tg-031e"></td>
  </tr>
</table>

提前谢谢

1 个答案:

答案 0 :(得分：0)

一种方法是按条目对meta_value进行分组，并将meta_value连接成一个字符串：

SELECT entry_id, GROUP_CONCAT(meta_value) AS meta_string
FROM your_table
GROUP BY entry_id

这将返回：

| 1 |地址1,1,2018-16-05，产品1 |

| 2 |地址2,1,2018-16-05，产品2 | 等

然后，您可以展开meta_string并构建表格，或者您可以将html作为分隔符放在查询中，如：

GROUP_CONCAT(meta_value ASC SEPARATOR '</td></tr><td>')

这将返回一个形式为：

的元数据 
Address 1</td><td>1</td><td>2018-16-05</td><td>Product 1

事实上，您需要在查询中添加tr和第一个/最后一个td / td的包装（参见下一个）或在您的代码中添加。

CONCAT('<tr><td>, GROUP_CONCAT(meta_value ASC SEPARATOR '</td></tr><td>', </td></tr>)) AS full_html_row

如果您需要meta_key，请执行相同的操作，但是这样：

SELECT entry_id, GROUP_CONCAT(meta_key) AS keys_string
FROM your_table
WHERE entry_id = 1
GROUP BY entry_id
UNION
SELECT entry_id, GROUP_CONCAT(meta_value) AS meta_string
FROM your_table
GROUP BY entry_id

另一种方法是，使用CASE来获得分隔列中的结果。但是，这不如在PHP或其他内容中旋转原始数据那样有效。

SELECT entry_id,
  MAX(CASE WHEN meta_key = 14 THEN meta_value ELSE NULL END) AS meta_value1,
  MAX(CASE WHEN meta_key = 20 THEN meta_value ELSE NULL END) AS meta_value2,
  MAX(CASE WHEN meta_key = 21 THEN meta_value ELSE NULL END) AS meta_value3,
  MAX(CASE WHEN meta_key = 23 THEN meta_value ELSE NULL END) AS meta_value4
FROM your_table
GROUP BY entry_id
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