为mysql列的总和创建函数

如何解决为mysql列的总和创建函数

我为d.cargaHr列的返回总和创建了此函数，但是无法创建此函数，并且此错误向我显示

错误（不允许从函数返回结果集）

   DELIMITER $$
    create function cargah_professor(idProfessor int,idCurso int)
    returns int 
    begin
        DECLARE sumCH int;
        SET sumCH=0;
        SELECT c.idCurso,d.nomedisciplina,p.idProfessor,d.cargaHr FROM curso c
        join disciplina d
        on d.Curso_idCurso = c.idCurso
        join turma t 
        on t.disciplina_iddisciplina = d.iddisciplina
        join professor p 
        on t.Professor_idProfessor = p.idProfessor
        where c.idCurso = idCurso and p.idProfessor = idProfessor;
        set sumCH = SUM(d.cargaHr);
        return sumCH;
    end
    $$