我想将以下查询组合成一个查询:
SELECT val FROM resource WHERE facet="all" and urlId="1234"
SELECT val FROM resource WHERE facet="your" and urlId="1234"
SELECT val FROM resource WHERE facet="base" and urlId="1234"
哦——每个 urlId 都有多个“方面”。但每个“方面”只有一行。这个表是别人设置的。我们正在迁徙。显然，每个“方面”都有一列和一行会更好，但为时已晚。
我可以用多个查询来做到这一点，但我想要一个更快/更好的解决方案。
<pre>
mysql> describe resource;
+-------------+-------------------------------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-------------------------------------+------+-----+-------------------+-----------------------------+
| resId | int(11) unsigned | NO | PRI | NULL | auto_increment |
| urlId | int(11) | NO | MUL | NULL | |
| sectionId | int(3) | YES | | NULL | |
| mode | enum('archive','live','edit','dev') | NO | | edit | |
| facet | varchar(50) | NO | MUL | NULL | |
| typeId | int(1) | NO | | 1 | |
| val | mediumtext | NO | | NULL | |
| itemOrder | tinyint(2) | NO | | 1 | |
| editorId | varchar(30) | NO | | NULL | |
| created | datetime | NO | | NULL | |
| lastUpdated | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+-------------+-------------------------------------+------+-----+-------------------+-----------------------------+
11 rows in set (0.05 sec)
</pre>
记住:在苏联，SQL 查询你。
最佳答案
这是我的首选方法，它将使用您的索引:
SELECT resource.val FROM
( (SELECT "all" AS name) UNION (SELECT "your") UNION (SELECT "base") ) AS facets
LEFT JOIN resource ON( resource.facet = facets.name AND resource.urlId = "1234" )
关于php - MySQL:我需要根据相同的条件将多行中的相同列名拉到单个查询中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6928483/