SQL Select 语法解决方法

Question

假设我有两个现有表，“狗”和“猫”:

 dog_name | owner
 ---------+------
 Sparky   | Bob
 Rover    | Bob
 Snoopy   | Chuck
 Odie     | Jon

 cat_name | owner
 ---------+------
 Garfield | Jon
 Muffy    | Sam
 Stupid   | Bob

How do I write a query with this output?

 owner | num_dogs | num_cats
 ------+----------+---------
 Bob   |     2    |    1
 Chuck |     1    |    0
 Sam   |     0    |    1
 Jon   |     1    |    1

The answer I've got is the next query

select owner, sum(num_dogs), sum(num_cats) from
  (select owner, 1 as num_dogs, 0 as num_cats from dogs
   union
   select owner, 0 as num_dogs, 1 as num_cats from cats)
group by owner

但问题是sql不支持“select * from (select...)” 查询类型

相反，在“from”之后必须有一个表名。

不幸的是我买不起临时 table 或 table 使用“select into”子句创建。我需要一些解决方法 以这种方式形成嵌套 select 子句的建议解决方案。

你怎么看？

干杯

Answer 1

我的 SQL 可以，只需要为表命名...您使用的是什么数据库？

 select owner, sum(num_dogs), sum(num_cats) from
  (select owner, 1 as num_dogs, 0 as num_cats from dogs
   union all
   select owner, 0 as num_dogs, 1 as num_cats from cats) as g
 group by owner