将两个mysql查询合并为一个

Question

组合这两个查询的正确语法是什么？

SELECT clicks FROM clicksTable WHERE clicks > 199 ORDER BY clicks ASC LIMIT 1

和

SELECT clicks FROM clicksTable ORDER BY clicks DESC LIMIT 1

我试过了：

SELECT clicks FROM clicksTable WHERE clicks > 199 ORDER BY clicks ASC LIMIT 1
UNION
SELECT clicks FROM clicksTable ORDER BY clicks DESC LIMIT 1;

但我得到“UNION和ORDER BY的使用不正确”。

修改 另外，我希望结果返回一行。这样我就可以访问php中的值，例如

$row['nextclick'] and $row['topclick'] 

根据Simon的建议，我不应该使用UNION，因为我想返回一行数据

Answer 1

您的第一个ORDER BY然后SELECT不能UNION。

修改
但是你可以

  

将ORDER BY或LIMIT应用于单个SELECT，将子句放在括起SELECT的括号内：

与MySQL UNION documentation

一样

(SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10)
UNION
(SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10);

然后制作你的SQL

(SELECT clicks FROM clicksTable WHERE clicks > 199 ORDER BY clicks ASC LIMIT 1)
UNION
(SELECT clicks FROM clicksTable ORDER BY clicks DESC LIMIT 1);

编辑2
要以array

返回

SELECT (SELECT clicks 
        FROM clicksTable 
        WHERE clicks > 199 
        ORDER BY clicks ASC 
        LIMIT 1) AS NextClick,
       (SELECT clicks 
        FROM clicksTable 
        ORDER BY clicks DESC 
        LIMIT 1) AS TopClick;

Answer 2

SELECT clicks FROM
    (SELECT clicks FROM clicksTable WHERE clicks > 199 ORDER BY clicks ASC LIMIT 1) A
UNION
SELECT clicks FROM
    (SELECT clicks FROM clicksTable ORDER BY clicks DESC LIMIT 1) B;

Answer 3

首先，您想要union还是union all？

问题是第一部分中的order by。您可以使用子查询修复此问题：

(select * from (SELECT clicks FROM clicksTable WHERE clicks > 199 ORDER BY clicks ASC LIMIT 1))
UNION ALL
(select * from (SELECT clicks FROM clicksTable ORDER BY clicks DESC LIMIT 1))

在union表达式中，order by仅在结尾处被允许，并且它适用于整个表达式。