How to find Duplicate entry cause in mysql?

Question

PHP

Hello! Mysql error constantly pops up when adding a record to the database, like this: Duplicate entry '' for key 2
How to find the reason for which field is duplicated?

Answer 1

SHOW INDEX FROM table_name where Non_unique = 0;
will print all unique indexes in the table.

Answer 2

Take a look at the composite unique indexes that have been created and you'll see what's going on.