oracle 년도별 group by

SELECT TO_CHAR(ibsadate,'YYYY') 입사년도 ,    COUNT(*) 인원수 FROM insa GROUP BY TO_CHAR(ibsadate,'YYYY') ORDER BY TO_CHAR(ibsadate,'YYYY');

출처: http://tibang.tistory.com/entry/오라클-GROUP-BY-그룹별-통계 [T없이맑은날]