[Oracle] SQL그룹함수, TO_CHAR함수, 서브쿼리
[1] SQL그룹함수 --count,sum,avg,max,min --1)count(*): null값 포함, 나머지는 null값 제외 select count(*),count(bonus),count(hpage) from professor; --2)sum select count(bonus),sum(bonus) from professor; --3)avg select count(bonus),sum(bonus),avg(bonus) from professor; --4)max,min select max(sal),min(sal) from emp; select max(hiredate),min(hiredate) from emp; --round: 소수점 지정 select round(avg(sal),1) from emp; --..
