Question

我试图创建一个处理两个表的查询：

表：REGION

Column Name     Type      Constraint
REGION_Cd       Number    Primary Key
REGION_Desc     String

表：STATS

Column Name     Type      Constraint
AGE             Number    Primary Key
REGION          Number    Foreign Key to REGION (REGION_Cd)
POPULATION      Number

我如何创建一个查询，以便找到两个年龄组（0-15,16-30）的人口并以下列格式显示：

Region_Desc    AgeGroup     Population
South          0‐15         11253
South          16‐30       235234

由于AgeGroup列实际上不是表中的一列，我应该使用AS语句，对吗？

Answer 1

也许类似......但它假设你想要年龄组/地区的人口总和。根据数据库中人口的工作方式，这可能是也可能不正确

Select Region_Desc, case when age between 0 and 15 then '0-15' 
  when age between 16 and 30 then '16-30' 
  else 'over 30' end as AgeGroup, 
sum(Population) as Population
FROM Region INNER JOIN STATS on region_Cd = Region
GROUP BY Region_DESC, AgeGroup

Answer 2

SELECT Region_DESC, AgeGroup, Population
FROM
(select REGION, sum(POPULATION) as Population, '0-15' AS AgeGroup
from STATS
Where Age between 0 and 15
group by REGION
union
Select REGION, SUM(POPULATION) as Population, '16-30' As AgeGroup
from STATS
Where Age between 16 and 30
group by REGION) s
join REGION on REGION_CD = REGION

使用AS的SQL查询

2 个答案: