How do I pull a substring of various sides? - sql

Question

If I want to update a column by pulling out only a part of a substring of another column.
What I want to do is pull the name of the jpg from the file and for example i want imageName to be equal to great-family.jpg" a varchar string. But the image names are all different.
update tblPetTips
set imageName = "great-family.jpg"
where articleText = "<img src="/images/imgs/great-family.jpg" alt="A Great Family Dog">"
In this case I would like to say
update tblPetTips
set imageName = "yellow-smile.jpg"
where articleText = "<img src="/images/imgs/yellow-smile.jpg" alt="A Yellow Smiley Face">"
How do I (without hardcoding) update imageName fromthe articleText column.
All the directories are the same - all the images live in images/imgs.

Answer 1

if the source of your images is always /images/imgs/, you can use patindex to find the position of '/images/imgs/' and '" alt', then extract the text between them.
check if this works:
substring(articletext,
patindex('/images/imgs/', articletext) + length('/images/imgs/'),
patindex('" alt') - (patindex('/images/imgs/', articletext) + length('/images/imgs/')))
if your images can have any url, then it would be feasible with regular expressions, but I don't think sqlserver provides regex directly.
in that case you could write a function to extract the filename part of a url and call it in the update.

Answer 2

You can try to get values between the last / and " with SUBSTRING_INDEX function:
UPDATE tblPetTips
SET imageName = SUBSTRING_INDEX(SUBSTRING_INDEX(articleText, '/', -1), '"', 1);
It will only work if format of <img srs=... > html is consistent.