SQL Server dynamic pivot table with dates as columns using CTE as my table? [duplicate] - sql

Question

This question already has answers here:
SQL Server dynamic PIVOT query?
(9 answers)
Closed 12 months ago.
So I have 36 month worth of data in my CTE, and the database is still active storing new data daily.
In my analysis, I just need 6 months worth of data from getdate()
So my question is that how do I make the month derived from calendar month the column of my table?
So for end of March 2022, this is the view that I should see:
id
name
10/01/21
11/01/21
12/01/21
01/01/22
02/01/22
03/01/2022
1
John
3
0
1
0
0
2
2
Mary
6
1
2
1
1
2
3
Angelo
1
5
3
2
2
0
4
Diane
3
2
0
1
0
6
So for the end of April 2022, this is the view that I should see:
id
name
11/01/21
12/01/21
01/01/22
02/01/22
03/01/2022
04/01/22
1
John
0
1
0
0
2
7
2
Mary
1
2
1
1
2
2
3
Angelo
5
0
0
0
0
3
4
Diane
2
0
1
0
6
4

Answer 1

You can't have a dynamic PIVOT without dynamic SQL. I find it's easiest to break it up into parts.
Get the last 6 months
DECLARE #thisMonth date, #firstMonth date;
SET #thisMonth = DATEFROMPARTS(YEAR(getdate()), MONTH(getdate()), 1);
SET #firstMonth = DATEADD(MONTH, -5, #thisMonth);
;WITH m(m) AS
(
SELECT #firstMonth
UNION ALL
SELECT DATEADD(MONTH, 1, m) FROM m
WHERE m < #thisMonth
)
SELECT m FROM m ORDER BY m DESC;
Output:
m
2022-03-01
2022-02-01
2022-01-01
2021-12-01
2021-11-01
2021-10-01
Figure out what manual query you need. Given this sample data:
CREATE TABLE dbo.JetSales
(
ID int,
Name nvarchar(32),
SalesDate date
);
INSERT dbo.JetSales(ID, Name, SalesDate) VALUES
(1,N'John','20211005'),(1,N'John','20211016'),(1,N'John','20211031'),
(2,N'Mary','20211007'),(2,N'Mary','20211013'),
(3,N'Tank','20211009');
I think you want a query like this (yes, you can accomplish this specific task with PIVOT too, but PIVOT doesn't cover some other scenarios, and it also requires pre-aggregation in this case... so I think conditional aggregation is better):
SELECT ID, Name,
[10/01/2021] = SUM(CASE WHEN SalesDate >= '20211001'
AND SalesDate < '20211101' THEN 1 ELSE 0 END),
[11/01/2021] = SUM(CASE WHEN SalesDate >= '20211101'
AND SalesDate < '20211201' THEN 1 ELSE 0 END),
[12/01/2021] = SUM(CASE WHEN SalesDate >= '20211201'
AND SalesDate < '20220101' THEN 1 ELSE 0 END),
[01/01/2022] = SUM(CASE WHEN SalesDate >= '20220101'
AND SalesDate < '20220201' THEN 1 ELSE 0 END),
[02/01/2022] = SUM(CASE WHEN SalesDate >= '20220201'
AND SalesDate < '20220301' THEN 1 ELSE 0 END),
[03/01/2022] = SUM(CASE WHEN SalesDate >= '20220301'
AND SalesDate < '20220401' THEN 1 ELSE 0 END)
FROM dbo.JetSales AS js GROUP BY ID, Name;
Which you can build as follows:
DECLARE #thisMonth date, #firstMonth date;
SET #thisMonth = DATEFROMPARTS(YEAR(getdate()), MONTH(getdate()), 1);
SET #firstMonth = DATEADD(MONTH, -5, #thisMonth);
DECLARE #sql nvarchar(max) = N'SELECT ID, Name';
;WITH m(m) AS
(
SELECT #firstMonth
UNION ALL
SELECT DATEADD(MONTH, 1, m) FROM m
WHERE m < #thisMonth
)
SELECT #sql += N',
' + QUOTENAME(CONVERT(char(10), m, 101))
+ N' = SUM(CASE WHEN SalesDate >= '
+ QUOTENAME(CONVERT(char(8), m, 112), char(39)) + N'
AND SalesDate < '
+ QUOTENAME(CONVERT(char(8), DATEADD(MONTH, 1, m), 112), char(39))
+ N' THEN 1 ELSE 0 END)'
FROM m;
SET #sql += N'
FROM dbo.JetSales AS js GROUP BY ID, Name;';
SELECT #sql;
EXEC sys.sp_executesql #sql;
Working example: db<>fiddle
If you really want to use PIVOT explicitly, you can, it's just a lot more cumbersome. Here's the query you want to end up with:
;WITH src AS
(
SELECT ID, Name, m = CONVERT(char(10),
DATEFROMPARTS(YEAR(SalesDate), Month(SalesDate), 1), 101)
FROM dbo.JetSales
WHERE SalesDate >= #firstMonth
),
agg AS
(
SELECT ID, Name, m, c = COUNT(*)
FROM src GROUP BY ID, Name, m
)
SELECT ID, Name,
[10/01/2021] = COALESCE([10/01/2021], 0),
[11/01/2021] = COALESCE([11/01/2021], 0),
[12/01/2021] = COALESCE([12/01/2021], 0),
[01/01/2022] = COALESCE([01/01/2022], 0),
[02/01/2022] = COALESCE([02/01/2022], 0),
[03/01/2022] = COALESCE([03/01/2022], 0)
FROM agg PIVOT (SUM(c) FOR m IN (
[10/01/2021],[11/01/2021],[12/01/2021],
[01/01/2022],[02/01/2022],[03/01/2022]
)) AS p;
To get there:
DECLARE #thisMonth date, #firstMonth date;
SET #thisMonth = DATEFROMPARTS(YEAR(getdate()), MONTH(getdate()), 1);
SET #firstMonth = DATEADD(MONTH, -5, #thisMonth);
DECLARE #col1 nvarchar(max) = N'',
#col2 nvarchar(max) = N'',
#sql nvarchar(max) = N';WITH src AS
(
SELECT ID, Name, m = CONVERT(char(10),
DATEFROMPARTS(YEAR(SalesDate), Month(SalesDate), 1), 101)
FROM dbo.JetSales
WHERE SalesDate >= #firstMonth
),
agg AS
(
SELECT ID, Name, m, c = COUNT(*)
FROM src GROUP BY ID, Name, m
)
SELECT ID, Name,';
;WITH m(m) AS
(
SELECT #firstMonth
UNION ALL
SELECT DATEADD(MONTH, 1, m) FROM m
WHERE m < #thisMonth
),
x(x) AS
(
SELECT QUOTENAME(CONVERT(char(10), m, 101)) FROM m
)
SELECT
#col1 += STRING_AGG(CONCAT(N'
', x, N' = COALESCE(', x, ',0)'),N','),
#col2 += STRING_AGG(x, N',
')
FROM x;
SET #sql += #col1 + N'
FROM agg PIVOT (SUM(c) FOR m IN ('
+ #col2 + N'
)) AS p;';
SELECT #sql;
EXEC sys.sp_executesql #sql, N'#firstMonth date', #firstMonth;
Another fiddle here: db<>fiddle