SQL查询可根据年龄段和

Question

I have employee table with some data as I've attached in the pictures below and want to query it to find the average salary and percentage of employee on each age range. I have used the following query but I don't know how to include the avarage and percentage result. Any help please.

SELECT emp.agerange as [age Range], count(emp.agerange) as [Number of employee on this age range]
FROM (
  SELECT CASE  
    WHEN age >60  THEN '60 And Up'
    WHEN age >=41 and age <=60 THEN '41-60'
    WHEN age >=21 and age <=40 THEN '21-40'
    WHEN age <=20 THEN '20 And Below' END as agerange
  from kin.dbo.Employee) emp
  group by emp.agerange 

Answer 1

You could use a cte to create your age groups, joining in any additional tables with info you want to work with, such as LoanBalance or Salary.

WITH emp as (
      SELECT CASE  
        WHEN age >60  THEN '60 And Up'
        WHEN age >=41 and age <=60 THEN '41-60'
        WHEN age >=21 and age <=40 THEN '21-40'
        WHEN age <=20 THEN '20 And Below' END as agerange
      ,l.LoanBalance -- might not be the field you are looking for
      from kin.dbo.Employee
      left join Loan l
      on ??????) -- You decide the join condition between these two tables

SELECT emp.agerange as [age Range]
,count(*) as [Number of employee on this age range]
,count(*) / (SELECT COUNT(*) FROM emp) as pctAgeRange
,(SELECT SUM(LoanBalance) / COUNT(*) FROM emp) as avgLoanBalance
FROM emp
  group by emp.agerange 

Answer 2

Does this work? I put your AgeRange function into a CTE.

WITH cteRange AS (
    SELECT ID,
        CASE  
            WHEN age > 60  THEN '60 And Up'
            WHEN age >= 41 and age <=60 THEN '41-60'
            WHEN age >= 21 and age <=40 THEN '21-40'
            WHEN age <= 20 THEN '20 And Below'
        END AS 'ageRange'
    FROM kin.dbo.Employee
)
SELECT cteRange.ageRange,
    COUNT(*) AS 'Number of Employees',
    SUM(emp.Salary) AS 'Total Salary',
    AVG(emp.Salary) AS 'Average Salary',
    ROUND(COUNT(*)/(SELECT COUNT(*) FROM kin.dbo.Employee)*100,2) AS '% Employees in age Range'
FROM kin.dbo.Employee AS emp
    INNER JOIN cteRange ON emp.ID = cteRange.ID
GROUP BY cteRange.ageRange

Answer 3

No need for joins, the average is a simple SQL AVG and the percentage can easily be calculated using a GROUP SUM:

SELECT emp.agerange as [age Range],
   count(*) as [Number of employee on this age range],
   SUM(Salary) AS "Total Salary",  
   AVG(Salary) AS "Average Salary",
   100 * COUNT(*) / SUM(COUNT(*)) OVER () AS "% of employees in this range"
FROM
 (
  SELECT Salary,
    CASE  
      WHEN age >60  THEN '60 And Up'
      WHEN age >=41 and age <=60 THEN '41-60'
      WHEN age >=21 and age <=40 THEN '21-40'
      WHEN age <=20 THEN '20 And Below' 
    END as agerange
  from kin.dbo.Employee
 ) emp
group by emp.agerange