How can I convert this PIVOT sql to CASE WHEN

I want to convert this PIVOT to CASE WHEN since I read that PIVOT is slow against a large database. Is it possible? I tried converting it BUT failed, it is displaying all the cmdocumentdefn.code COUNT which is 50. I want to count the code by weekday i.e.

MON  TUE  WED .... SUN
8     2    4        1

The query is:

SELECT * FROM
    (SELECT 
        cmdocumentdefn.code, cmdocumentdefn.description 'description',
        CASE DatePart(weekday,cmrevisionaddress.issueddate)
        WHEN 1 THEN 'SUN'
        WHEN 2 THEN 'MON'
        WHEN 3 THEN 'TUE' 
        WHEN 4 THEN 'WED'
        WHEN 5 THEN 'THU'
        WHEN 6 THEN 'FRI'
        WHEN 7 THEN 'SAT'
        END  'dayx'    
    FROM cmdocumentdefn
        INNER JOIN
        cmdocument
        ON cmdocumentdefn.cmdocumentdefn = cmdocument.cmdocumentdefn
        INNER JOIN cmrevisionaddress
        ON cmdocument.cmdocument = cmrevisionaddress.cmdocument WHERE cmdocumentdefn.code = 'AF') x
    PIVOT(COUNT(dayx) FOR dayx IN([MON],[TUE],[WED],[THU],[FRI],[SAT],[SUN])) pvt

Solution

DECLARE @data TABLE (ID int, Code nvarchar(10), Description nvarchar(100), DocDate datetime) 
INSERT INTO @data VALUES(1, 'FA', 'lorem ipsum 1', '2021-07-05')
INSERT INTO @data VALUES(2, 'FA', 'lorem ipsum 2', '2021-07-05')
INSERT INTO @data VALUES(3, 'FA', 'lorem ipsum 3', '2021-07-05')
INSERT INTO @data VALUES(4, 'FA', 'lorem ipsum 4', '2021-07-05')
INSERT INTO @data VALUES(5, 'SH', 'lorem ipsum 5', '2021-08-31')
INSERT INTO @data VALUES(6, 'SH', 'lorem ipsum 6', '2021-08-31')
INSERT INTO @data VALUES(7, 'SH', 'lorem ipsum 7', '2021-08-31')
INSERT INTO @data VALUES(8, 'AG', 'lorem ipsum 8', '2021-09-15')
INSERT INTO @data VALUES(9, 'AG', 'lorem ipsum 9', '2021-09-15')
INSERT INTO @data VALUES(10, 'XX', 'lorem ipsum 10', '2021-10-21')


SELECT Code, Description, 
        IIF(DATEPART(weekday, DocDate) = 1, 1, 0) AS SUN,
        IIF(DATEPART(weekday, DocDate) = 2, 1, 0) AS MON,
        IIF(DATEPART(weekday, DocDate) = 3, 1, 0) AS TUE,
        IIF(DATEPART(weekday, DocDate) = 4, 1, 0) AS WED,
        IIF(DATEPART(weekday, DocDate) = 5, 1, 0) AS THU,
        IIF(DATEPART(weekday, DocDate) = 6, 1, 0) AS FRI,
        IIF(DATEPART(weekday, DocDate) = 7, 1, 0) AS SAT
FROM @data

I took the 1st 10 rows of the example data. This is the result:

If you want the sum for each code then this is the query:

SELECT Code,  
        SUM(IIF(DATEPART(weekday, DocDate) = 1, 1, 0)) AS SUN,
        SUM(IIF(DATEPART(weekday, DocDate) = 2, 1, 0)) AS MON,
        SUM(IIF(DATEPART(weekday, DocDate) = 3, 1, 0)) AS TUE,
        SUM(IIF(DATEPART(weekday, DocDate) = 4, 1, 0)) AS WED,
        SUM(IIF(DATEPART(weekday, DocDate) = 5, 1, 0)) AS THU,
        SUM(IIF(DATEPART(weekday, DocDate) = 6, 1, 0)) AS FRI,
        SUM(IIF(DATEPART(weekday, DocDate) = 7, 1, 0)) AS SAT
FROM @data
GROUP BY Code

And the result: