Question

我必须从同一个表加入3个查询。我试过这段代码：

SELECT t1.`board`
      ,t1.`price`
      ,t2.`price`
      ,t3.`price`
  from boardtype t1
  RIGHT JOIN(SELECT `price`
      from boardtype
      WHERE `acnonac`='ac' AND `roomtype`='single')
  t2 on t1.`board` = t2.`board`
  RIGHT JOIN(
      SELECT 
      `price`
      from boardtype 
      WHERE `acnonac`='ac' AND `roomtype`='double'
  ) t3 on t1.`board` = t3.`board`
WHERE `acnonac`='ac' AND `roomtype`='triple'
ORDER by id

简单地说我正在尝试加入这三个问题：

SELECT `board`,`price` FROM boardtype WHERE `acnonac`='ac' AND `roomtype`='single'
SELECT `board`,`price` FROM boardtype WHERE `acnonac`='ac' AND `roomtype`='double'
SELECT `board`,`price` FROM boardtype WHERE `acnonac`='ac' AND `roomtype`='triple'

我不知道我犯了什么错误。

Answer 1

您的子选择中没有board，但您使用它们编写ON子句。

将board添加到子选择：

SELECT t1.`board`
      ,t1.`price`
      ,t2.`price`
      ,t3.`price`
  from boardtype t1
  RIGHT JOIN
      (SELECT `price`, `board`
      from boardtype
      WHERE `acnonac`='ac' AND `roomtype`='single') t2 on t1.`board` = t2.`board`
  RIGHT JOIN(
      SELECT `price`, `board`
      from boardtype
      WHERE `acnonac`='ac' AND `roomtype`='double') t3 on t1.`board` = t3.`board`
WHERE `acnonac`='ac' AND `roomtype`='triple'
ORDER by id

Answer 2

也许效率更高

SELECT `boardtype`.`board`
      ,`boardtype`.`price`
  from `boardtype` WHERE `boardtype`.`acnonac`='ac' AND `boardtype`.`roomtype` IN ('single', 'double', 'triple')

<强>感谢

从同一个表加入三个查询

2 个答案: