T-SQL update with switch-case statement - sql

Question

I want implement this pseudocode in t-sql
UPDATE Resources SET [Path]= CASE ([Path].Substring([Path].LastIndexOf('.')))
WHEN '.jpg' THEN '/image.jpg'
WHEN '.png' THEN '/image.jpg'
WHEN '.avi' THEN '/video.jpg'
WHEN '.mkv' THEN '/video.jpg'
for it I use this solution
UPDATE Resources SET [Path] = CASE (SUBSTRING([Path], LEN([Path]) - CHARINDEX('.', REVERSE([Path])) + 1, 3))
WHEN '.jpg' THEN '/image.jpg'
WHEN '.png' THEN '/image.jpg'
WHEN '.avi' THEN '/video.jpg'
WHEN '.mkv' THEN '/video.jpg'
END
but it is does not return expected result.
Can anyone give me working version please?

Answer 1

UPDATE
Resources
SET
Path = CASE SUBSTRING(Path, LEN(Path) - CHARINDEX('.', REVERSE(Path)) + 1, 4)
WHEN '.jpg' THEN '/image.jpg'
WHEN '.png' THEN '/image.jpg'
WHEN '.avi' THEN '/video.jpg'
WHEN '.mkv' THEN '/video.jpg'
END

Answer 2

Instead of SUBSTRING([Path], LEN([Path]) - CHARINDEX('.', REVERSE([Path])) + 1, 3),
try using lower(right([Path], 4))

Answer 3

Your read of the extension is wrong, instead try:
SUBSTRING(Path, LEN(Path) - CHARINDEX('.', REVERSE(Path)) + 1, LEN(Path))
(Using LEN(Path) as the read length; fine if it overflows the end of the string and allows for n-character extensions)

Answer 4

Try using the ParseName
UPDATE Resources SET [Path] = CASE (Parsename(Path,1))
WHEN 'jpg' THEN '/image.jpg'
WHEN 'png' THEN '/image.jpg'
WHEN 'avi' THEN '/video.jpg'
WHEN 'mkv' THEN '/video.jpg'
END

Answer 5

UPDATE Resources SET ThumbnailPath = CASE SUBSTRING(ThumbnailPath, LEN(ThumbnailPath) - CHARINDEX('.', REVERSE(ThumbnailPath)) + 1, LEN(ThumbnailPath))
WHEN '.doc' THEN #root + '/doc.png'
WHEN '.docx' THEN #root + '/doc.png'
WHEN '.jpg' THEN #root + '/image.png'
WHEN '.jpeg' THEN #root + '/image.png'
WHEN '.gif' THEN #root + '/image.png'
WHEN '.png' THEN #root + '/image.png'
WHEN '.ppt' THEN #root + '/ppt.png'
WHEN '.pptx' THEN #root + '/ppt.png'
WHEN '.pdf' THEN #root + '/pdf.png'
ELSE #root + '/other.png'
END
thank you I finaly use this

Answer 6

This script will assure that you do not update all rows every time you run the script. It will only update changes.
UPDATE r
SET ThumbnailPath = newvalue
FROM Resources r
cross apply
(SELECT right(ThumbnailPath, patindex('%_.%', reverse(ThumbnailPath))) T) a
cross apply
(SELECT CASE
WHEN a.T in ('doc','docx' ) THEN #root + '/doc.png'
WHEN a.T in ('jpg','jpeg','gif','png') THEN #root + '/image.png'
WHEN a.T in ('ppt','pptx') THEN #root + '/ppt.png'
WHEN a.T = 'pdf' THEN '/pdf.png'
ELSE #root + '/other.png'
END newvalue) b
WHERE r.ThumbnailPath <> b.newvalue