ORDER BY the Items Within a Case Statement - tsql

Question

Is there another way I can sort the results by the Age Group appropriately? As a work-around, I placed a character before each age group to display in chronological order - but if the letter is not there, then it does not display in the order I am expecting. Here is the T-SQL:
WITH AgeData
AS ( SELECT DATEDIFF(YEAR, birthDate, GETDATE()) - CASE WHEN GETDATE() < DATEADD(YEAR , DATEDIFF(YEAR, birthDate, GETDATE()), birthDate )
THEN 1
ELSE 0
END AS [Age]
FROM dbo.Customers ) ,
GroupAge
AS ( SELECT [Age] ,
CASE WHEN AGE < 4 THEN 'a0 - 3'
WHEN AGE BETWEEN 4 AND 8 THEN 'b4 - 8'
WHEN AGE BETWEEN 9 AND 12 THEN 'c9 - 12'
WHEN AGE BETWEEN 13 AND 17 THEN 'd13 - 17'
WHEN AGE BETWEEN 18 AND 22 THEN 'e18 - 22'
WHEN AGE BETWEEN 23 AND 26 THEN 'f23 - 26'
WHEN AGE BETWEEN 27 AND 33 THEN 'g27 - 33'
WHEN AGE BETWEEN 34 AND 40 THEN 'h34 - 40'
WHEN AGE BETWEEN 41 AND 50 THEN 'i41 - 50'
WHEN AGE BETWEEN 51 AND 60 THEN 'j51 - 60'
WHEN AGE BETWEEN 61 AND 65 THEN 'k61 - 65'
WHEN AGE BETWEEN 66 AND 74 THEN 'l66 - 74'
WHEN AGE > 75 THEN 'm75+'
ELSE 'nInvalid Birthdate'
END AS [AgeGroups]
FROM AgeData
)
SELECT COUNT(*) AS [AgeGroupCount] ,
[AgeGroups]
FROM GroupAge
GROUP BY GroupAge.[AgeGroups]
ORDER BY GroupAge.[AgeGroups];
Without the character such as 'a', 'b', 'c', etc... my result set looks like:
If possible, I'd like to sort correctly without the work-around of using a letter.

Answer 1

You could add one more column to order item
WITH AgeData
AS (
SELECT DATEDIFF(YEAR, birthDate, GETDATE()) -
CASE
WHEN GETDATE() < DATEADD(YEAR , DATEDIFF(YEAR, birthDate, GETDATE()), birthDate )
THEN 1
ELSE 0
END AS [Age]
FROM dbo.Customers ) ,
GroupAge
AS ( SELECT [Age] ,
CASE WHEN AGE < 4 THEN '0 - 3'
WHEN AGE BETWEEN 4 AND 8 THEN '4 - 8'
WHEN AGE BETWEEN 9 AND 12 THEN '9 - 12'
WHEN AGE BETWEEN 13 AND 17 THEN '13 - 17'
WHEN AGE BETWEEN 18 AND 22 THEN '18 - 22'
WHEN AGE BETWEEN 23 AND 26 THEN '23 - 26'
WHEN AGE BETWEEN 27 AND 33 THEN '27 - 33'
WHEN AGE BETWEEN 34 AND 40 THEN '34 - 40'
WHEN AGE BETWEEN 41 AND 50 THEN '41 - 50'
WHEN AGE BETWEEN 51 AND 60 THEN '51 - 60'
WHEN AGE BETWEEN 61 AND 65 THEN '61 - 65'
WHEN AGE BETWEEN 66 AND 74 THEN 'l66 - 74'
WHEN AGE > 75 THEN 'm75+'
ELSE 'nInvalid Birthdate'
END AS [AgeGroups],
CASE WHEN AGE < 4 THEN 1
WHEN AGE BETWEEN 4 AND 8 THEN 2
WHEN AGE BETWEEN 9 AND 12 THEN 3
WHEN AGE BETWEEN 13 AND 17 THEN 4
WHEN AGE BETWEEN 18 AND 22 THEN 5
WHEN AGE BETWEEN 23 AND 26 THEN 6
WHEN AGE BETWEEN 27 AND 33 THEN 7
WHEN AGE BETWEEN 34 AND 40 THEN 8
WHEN AGE BETWEEN 41 AND 50 THEN 9
WHEN AGE BETWEEN 51 AND 60 THEN 10
WHEN AGE BETWEEN 61 AND 65 THEN 11
WHEN AGE BETWEEN 66 AND 74 THEN 12
WHEN AGE > 75 THEN 13
ELSE 14
END AS [AgeGroupId]
FROM AgeData
)
SELECT COUNT(*) AS [AgeGroupCount] ,
[AgeGroups]
FROM GroupAge
GROUP BY GroupAge.[AgeGroups],[AgeGroupId]
ORDER BY GroupAge.[AgeGroupId]
Another solution: Use a temp table that contains group information
DECLARE #GroupAge AS TABLE
(
GroupID int,
StartAge int,
EndAge int,
GroupName AS CONCAT(StartAge, '-', EndAge)
)
INSERT INTO #GroupAge
(
GroupID,
StartAge,
EndAge
)
VALUES (1,0,3) -- insert all groups you need
;WITH AgeData
AS (
SELECT DATEDIFF(YEAR, birthDate, GETDATE()) -
CASE
WHEN GETDATE() < DATEADD(YEAR , DATEDIFF(YEAR, birthDate, GETDATE()), birthDate )
THEN 1
ELSE 0
END AS [Age]
FROM dbo.Customers )
SELECT COUNT(*) AS [AgeGroupCount] ,
ga.GroupName
FROM AgeData a
INNER JOIN #GroupAge ga ON ( a.Age BETWEEN ga.StartAge AND ga.EndAge)
GROUP BY ga.GroupID, ga.GroupName
Order By ga.GroupID

Answer 2

In your ORDER BY clause, just add the following line:
IIF([AgeGroups] = 'Invalid Birthdate', 999, CAST(LEFT([AgeGroups], CHARINDEX('-', REPLACE([AgeGroups], '+', '-'))- 1) AS INT))
This is full working example:
DECLARE #DataSource TABLE
(
[AgeGroups] VARCHAR(18)
);
INSERT INTO #DataSource
VALUES ('0-3')
,('13-17')
,('18-22')
,('23-26')
,('27-33')
,('34-40')
,('4-8')
,('41-50')
,('51-60')
,('61-65')
,('66-74')
,('75+')
,('9-12')
,('Invalid Birthdate');
SELECT *
,IIF([AgeGroups] = 'Invalid Birthdate', 999, CAST(LEFT([AgeGroups], CHARINDEX('-', REPLACE([AgeGroups], '+', '-'))- 1) AS INT))
FROM #DataSource
ORDER BY IIF
(
[AgeGroups] = 'Invalid Birthdate'
,999
,CAST(LEFT([AgeGroups], CHARINDEX('-', REPLACE([AgeGroups], '+', '-'))- 1) AS INT)
);
The idea is to get the start number for each range, covert it to number and sort by it. We just need to add extra check for the Invalid Birthdate string and replace the + with - for the 75+ value.