How to remove last occurrence of OR from string

Question

I just want to ask that I want to remove the last OR from following string.

$string = 'b.dates LIKE "2017-10-13%" OR 
b.dates LIKE "2017-10-14%" OR 
b.dates LIKE "2017-10-15%" OR 
b.dates LIKE "2017-10-16%" OR 
b.dates LIKE "2017-10-17%" OR';

Answer 1

$ character indicates the end of string.

preg_replace("/OR$/", '', $str );

or

rtrim($str, ' OR');