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（20个条目）中的前10个男性和前10个女性？这可能吗？

Answer 1

正确的语法使用括号和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

这是可能的，它被称为UNION

Answer 3

您可以使用UNION运营商。

UNION用于组合多个SELECT语句的结果到一个结果集。

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

使用ROW_NUMBER（）

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

SQL Query包含2个结果集

5 个答案: