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

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)