sql - MySQL BEFORE INSERT trigger to turn duplicate primary keys inserts into updates -

i'm trying execute query in database through phpmyadmin

create trigger avoid_duplicated_sharing before insert on sharingevents each row begin   if ( select count(*) sharingevents shared_note_id = new.shared_note_id , shared_to = new.shared_to  > 0 )       delete sharingevents shared_note_id = new.shared_note , shared_to = new.shared_to   end if; end 

but phpmyadmin gives me following error:

mysql said: #1064 - have error in sql syntax; check manual corresponds mariadb server version right syntax use near 'end if' @ line 7

two questions:

• what's wrong script?
• after before insert trigger, insert operation performed? in case doesn't have remove insert sharingevents (select * new);

i solve following code:

delimiter $$  create trigger avoid_duplicated_sharing before insert on sharingevents each row begin     if ( select count(*) sharingevents shared_note_id = new.shared_note_id , shared_to = new.shared_to  > 0 )         delete sharingevents shared_note_id = new.shared_note_id , shared_to = new.shared_to;     end if; end$$ 

the problem delimiter.

even so, trigger doesn't work. when application inserts duplicated primary keys mysql throws following error:

#1442 - can't update table 'sharingevents' in stored function/trigger because used statement invoked stored function/trigger.