create procedure searchStudentGrade(in id char) begin if id is null select student.StudentID,student.StudentName,student.ClassNumber,grade.ExamID,course.CourseName,grade.Grade,course.CourseID from student,grade,course where student.StudentID=grade.StudentID and grade.CourseID=course.CourseID; else select student.StudentID,student.StudentName,student.ClassNumber,grade.ExamID,course.CourseName,grade.Grade,course.CourseID from student,grade,course where student.StudentID=grade.StudentID and grade.CourseID=course.CourseID and grade.StudentID=id; end if;end;