SQL Aggregate records by CASE WHEN - sql

Question

I am trying to aggregate the records' sum depending on the value that match the CASE WHEN
I am able to aggregate the sum but I don't know how I can group the records depending on the description value.
SQL Query:
SELECT
T1.Company, T1.DueDate,
SUM(T1.Amount) AS TotalAmount,
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) AS Age,
CASE
WHEN
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 0
THEN
'Current'
WHEN
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) > 0
AND DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 30
THEN
'Late'
END AS Description
FROM
Table1 T1
LEFT JOIN
Table2 T2
ON T1.Company = T2.Company
AND T1.YR = T2.YR
INNER JOIN
Table3 T3
ON T1.Company = T3.Company
AND T3.YR = YEAR(CURRENT_DATE)
GROUP BY T1.Company,T1.DueDate, T3.FromDate
My query returns the following.
Company | DueDate | TotalAmount | Age | Description
------------+----------------+-------------+------+------------
123 | 20200423 | 150 | 7 | Late
123 | 20200604 | 18000 | -35 | Current
123 | 20200515 | 500 | -15 | Current
However, what I really want to accomplish is to aggregate records if they have same Description value.
So, the correct result should be :
Company | TotalAmount |Description |
------------+--------------+------------+
123 | 150 | Late
123 | 18500 | Current
The 2nd and 3rd row falls under "Current". Therefore, it should combine the 2 rows and add 18000 + 500 = 18500. DueDate and Age column is just for reference. The most important fields are TotalAmount and Description
I tried grouping by the alias Description which is used in CASE-WHEN but I didn't work.
I'd appreciate any help.
Thanks!

Answer 1

You copy-and-paste the CASE statement into the GROUP BY clause:
GROUP BY T1.Company, CASE WHEN ...
which is a lot of code to repeat.
Or you can use a common table expression (CTE):
;WITH
cte AS
(
SELECT
T1.Company, T1.DueDate, T1.Amount
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) AS Age,
CASE
WHEN
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 0
THEN
'Current'
WHEN
DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) > 0
AND DATEDIFF( day, CONVERT(DATETIME, CAST(T1.DueDate AS VARCHAR(8)), 112), DATEADD( day, - 1, CONVERT(DATETIME, CAST(T3.FromDate AS VARCHAR(8)), 112) ) ) <= 30
THEN
'Late'
END AS Description
FROM
Table1 T1
LEFT JOIN
Table2 T2
ON T1.Company = T2.Company
AND T1.YR = T2.YR
INNER JOIN
Table3 T3
ON T1.Company = T3.Company
AND T3.YR = YEAR(CURRENT_DATE)
)
SELECT Company, Description, SUM(Amount) AS TotalAmount
FROM cte
GROUP BY Company, Description