合并2个查询与不同的WHERE子句

Question

我有以下查询：

select 
* 
from 
(
SELECT art_titel as at, COUNT(*) as Number1 
FROM artikel_views 
WHERE user_id != '' 
GROUP BY art_titel 
ORDER BY Number1 desc 
) as FirstSet 
join 
(
SELECT art_titel as at, COUNT(*) as Number2 
FROM artikel_views 
WHERE user_id = '' 
GROUP BY art_titel 
ORDER BY Number2 desc 
) as SecondSet 
on FirstSet.at = SecondSet.at 

我的HTML表：

<table> 
    <tr> 
    <td>Art Titel</td> 
    <td>user_id is NULL</td> 
    <td>user_id is not NULL</td> 
    </tr> 

<?php while($row = mysql_fetch_assoc($res)) { ?> 

    <tr> 
    <td><?php echo $row['at']; ?></td> 
    <td><?php echo $row['Number2']; ?></td> 
    <td><?php echo $row['Number1']; ?></td> 
    </tr> 

<?php } ?> 

</table> 

我要做的就是从$行[ '数字1']取值和$ row ['Number 2']结合art_titel。 该查询的结果不好。在这两个查询中，我只有art_titel和art_titel上art_titel的匹配，但效果并不好。我需要两种方式的所有项目。

我也试过一个联盟，但是不是我的方式工作。

Answer 1

不需要2个查询，只需使用CASE条件。

SELECT art_titel as at, SUM(CASE WHEN user_id != '' THEN 1 ELSE 0 END) as Number1, 
SUM(CASE WHEN user_id = '' THEN 1 ELSE 0 END) as Number2 
FROM artikel_views 
GROUP BY art_titel 
ORDER BY Number1 desc,Number2 desc