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}%%'

https://stackoverflow.com/questions/8616829/mysql-wildcards-vs — Mihir Dave, Jun 14 '18 at 17:54

score 5 · Accepted Answer · answered Jun 14 '18 at 18:02

5

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:

answered Jun 14 '18 at 18:02

Bill Karwin

538,548
86
673
828

Forget it to mention, the environment is Yii1/PHP. Thanks. – szatti1489 Jun 14 '18 at 18:07
I haven't used Yii. Is it possible it's using `%{fullname}%` as a token to replace with some content, and then the extra `%` characters on either side are the actual SQL wildcards? – Bill Karwin Jun 14 '18 at 18:11

questionto42 · Answer 2 · 2020-07-21T07:35:06.527

1

I doubt that it is a legacy issue. I have used double percent in python 3.7 as well, though admittedly on an older mysql version, with double percent having the only function of escaping the second %. I came to this by Python3.8, MySQL5.7: passing active wildcards to LIKE query

edited Jul 21 '20 at 07:35

answered Jul 20 '20 at 21:54

questionto42

7,175
4
57
90

mysql LIKE with double percent

2 Answers2

Linked