Select * from student where empty(regno) or empty(name) or val(sys11(dob))=0 or empty(course) or empty(category) order by name

>I have student.dbf with fileds 1.regno(C), 2.name(C), 3.dob(D), 4.Course(C), 5.category(C)
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>How to write SQL Query for find empty value of all field of my "student.dbf" table?