there are two tables table A
if user use this query \"insert into A values(abc,1,50);\"
then trigger should check student_nam
try like this...
if (Select Count(Name) from B where B.Name=new.name)<1 insert into summary_score (name,number,all_marks) values(new.name,new.marks,new.score); else update B set all_marks=old.all_marks+new.student_marks where B.Name=new.Name;