使用 AS 的 SQL 查询 [英] SQL Query using AS

问题描述

我正在尝试创建一个处理两个表的查询:

I'm trying to create a query which deals with two tables:

表格:区域

Column Name     Type      Constraint
REGION_Cd       Number    Primary Key
REGION_Desc     String

表格:统计数据

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)的人口并以以下格式显示:

How could I create a query such that it finds the population for two age groups (0-15, 16-30) and displayed in the following format:

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

因为 AgeGroup 列实际上不是表中的列，所以我应该使用 AS 语句，对吗?

Since the AgeGroup column isnt actually a column in the tables, I should be using an AS statement, correct?

推荐答案

也许类似于...但它假设您想要年龄组/地区的人口总和.根据人口在数据库中的工作方式，这可能正确也可能不正确

Perhaps something like... but it assumes you want sum of population in age group/region. which may or maynot be correct depending on how population works in the database

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

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