mysql LIKE with double percent

Question

I just debugging a legacy code and I found a strange part in it. Does anybody has an idea, what does the following mean in the MYSQL string?

full_name LIKE '%%{fullname}%%'

Answer 1

As in the answer Mihir Dave's comment links to, there's no difference to SQL if you pass %% instead of %. Since a single % matches zero or more characters, then each of the metacharacters in %% would also match zero or more, and ultimately the same string would match one way or another.

But I'd guess your legacy code is pre-Python 2.6 that uses % as a metacharacter in string formatting, and you have to double it like %% to get a single literal % character.

See also:

• How can I selectively escape percent (%) in Python strings?
• https://docs.python.org/2.6/library/stdtypes.html#string-formatting-operations