Count characters after given symbol in oracle varchar column value

Question

How would I go about counting the characters after a certain character. I'm new to Oracle, and I've learned quite a bit however I'm stumped at this point. I found a couple functions that will get you a substring and I found a function that will give you the length of a string. I am examining an email address, myemail@thedomain.com. I want to check the length after the '.' in the email.

SELECT email
FROM user_table
WHERE length(substr(email, /*what values*/, /*to put here*/))

I don't know if it's actually possible to find the location of the final '.' in the email string?

Answer 1

I'm not sure I would use substr. You can try something like this :

select length('abcd@efgh.123.4567') - instr('abcd@efgh.123.4567', '.', -1) from dual

Using instr(..,..,-1) searches backwards from the last character to find the position.

Answer 2

Since you're doing checks, I suggest you validate the format with regular expressions using REGEXP_INSTR. For instance, an email validation I found on this site is REGEXP_INSTR(email, '\w+@\w+(\.\w+)+') > 0

I didn't check it myself, but it looks quite ok.

Cheers.