i want to execute the following query using execute, it works perfect with select but when i call it in trigger i get this error "ERROR: query has no destination for result data ". I 've tried perform but it doesn't work. The function in select insert rows in a table.

select insert_new_grade('title0', return3_6(0), return3_6(1), return3_6(2), s.code)
FROM "student" as s
where find_st(s.grade)>=5;

So i've thought of EXECUTE but i get syntax errors . Here is my try :

execute 'insert_new_grade('title0', return3_6(0), return3_6(1), return3_6(2), s.code)
FROM "student" as s
where find_st(s.grade)>=5';

Can someone tell me what im doing wrong ? Or is there any other idea to make the query work in the trigger function? Thanks in advance..

Here is the trigger :

CREATE OR REPLACE FUNCTION insert_d() 
RETURNS TRIGGER AS $$ 
BEGIN
    select insert_new_grade('title0', return3_6(0), return3_6(1), return3_6(2), s.code)
    FROM "student" as s
    where find_st(s.grade)>=5;

    return new;
END;
$$ LANGUAGE plpgsql; 

and here is the insert function :

CREATE OR REPLACE FUNCTION insert_new_diploma(title0 character(100), prof0 character(11), prof1 character(11)) 
RETURNS VOID AS $$
BEGIN
    INSERT INTO "d_table"(thes0, title, grade, prof, secProf) 
    VALUES (null, title0, null, prof0, prof1);
END
$$
LANGUAGE 'plpgsql';