There is a simple INSERT. How to make a check when writing two fields so that it does not write a duplicate?

Question

PHP

supports_user table:

id    |   support_id   |   client_id
1     |          2        |       13
2     |          2        |       13

$query1 = "INSERT INTO supports_user (support_id, client_id) VALUES ('$support_id', '$client_id')";

How to avoid such duplication? What if there is such a support_id with the same client_id, then do not write it down?

Answer 1

https://dev.mysql.com/doc/refman/8.0/en/replace.html