Question

MYSQL（version5.1）中以下查询的GOT错误

SELECT year,month,sum(fact_1),sum(fact_2),sum(fact_3),sum(fact_4)
from(
select year,month,fact_1,fact_2,0 as fact_3,0 as fact_4 from table_1
intersect
select year,month,0 as fact_1,0 as fact_2,fact_3,fact_4 from table_2
) as combined_table
group by month,year

代码为＃1064的错误行： -

您的SQL语法有错误; 检查对应的手册您的MySQL服务器版本正确的语法在'select附近使用年，月，0为fact_1,0 as fact_2，fact_3，fact_2从table_2）as ct g'在第5行

但是以下查询给出了所需的结果： -

SELECT year,month,sum(fact_1),sum(fact_2),sum(fact_3),sum(fact_4)
from(
select year,month,fact_1 ,fact_2,0 as fact_3,0 as fact_4 from table_1
union
select year,month,0 as fact_1,0 as fact_2,fact_3,fact_4 from table_2
) as ct
group by month,year

有人可以告诉我犯了什么错误吗？任何人都可以帮助我理解问题背后的根本原因。

Answer 1

您可以使用INTERSECT（自我）INNER轻松伪造JOIN，这样您只能从两个结果集中获取行：

    SELECT `a`.`id`, `a`.`name`
      FROM `a`
INNER JOIN `b`
     USING (`id`, `name`)

MINUS可伪造成LEFT JOIN：

    SELECT DISTINCT `a`.`id`, `a`.`name`
      FROM `a`
 LEFT JOIN `b`
     USING (`id`, `name`)
     WHERE `b`.`id` IS NULL

Answer 2

MySQL不支持INTERSECT关键字。 SELECT for 5.1的完整语法如下：

http://dev.mysql.com/doc/refman/5.1/en/select.html

任何人都可以提出“交叉”的替代方案; MYSQL的“减号”？

2 个答案: