SQL查询包含2个结果集

Question

select name from persons where gender = 'male' order by name limit 10

select name from persons where gender = 'female' order by name limit 10

如何通过单个SQL查询调用获得单个结果集中（前20个条目）的前10位男性和前10位女性？ 这可能吗？

Answer 1

正确的语法使用括号并将union all并union all ：

(select name
 from persons
 where gender = 'male'
 order by name
 limit 10
) union all
(select name
 from persons
 where gender = 'female'
 order by name
 limit 10
)

Answer 2

有可能，它叫做UNION

Answer 3

您可以使用UNION运算符。

UNION用于将来自多个SELECT语句的结果合并为一个结果集。

select name from persons where gender = 'male' order by name limit 10
UNION
select name from persons where gender = 'female' order by name limit 10

Answer 4

  SELECT name FROM persons WHERE gender = 'male' ORDER BY name LIMIT 0,10 ;
  UNION 
 SELECT name FROM persons WHERE gender = 'female' ORDER BY name LIMIT 0,10 ;

Answer 5

与ROW_NUMBER（）

SELECT * FROM (
SELECT ROW_NUMBER() OVER (PARTITION BY gender ORDER BY gender) row_no,*  FROM Person
) A WHERE A.row_no <= 10