MySQL error in file: /var/www/fastuser/data/www/shop.aikidoka.ru/engine/modules/show.short.php at line 66

Error Number: 3685

The Error returned was:
Illegal argument to a regular expression.

SQL query:

SELECT id, autor, date, short_story, full_story, xfields, title, category, alt_name FROM shop_post WHERE category regexp '[[:<:]](31)[[:>:]]' AND approve=1 AND date < '2023-09-22 14:23:19' ORDER BY date DESC LIMIT 0,10