following code gives the error message: "ORA-00979: not a GROUP BY expression", how do I fix this?
select ssn, category, min_units - sum(units) "UNITS_LEFT"
from course
where category = category
group by ssn
additional info:
table course: SSN SECTION UNITS COURSE CATEGORY MIN_UNITS
select ssn, category, min_units - sum(units) "UNITS_LEFT"
from course
where category = category
group by ssn
additional info:
table course: SSN SECTION UNITS COURSE CATEGORY MIN_UNITS