행열 변환2 (가로 -> 세로)

 

년도를 행으로 표시

 

SELECT MM
       , SUM(CASE WHEN YR=1998 THEN CNT ELSE 0 END) AS BEFOREYEAR
       , SUM(CASE WHEN YR=1999 THEN CNT ELSE 0 END) AS THISYEAR
  FROM (SELECT YEAR(HIRE_DATE) YR
               , MONTH(HIRE_DATE) AS MM
               , COUNT(*) AS CNT
       	  FROM EMPLOYEES 
	     WHERE YEAR(HIRE_DATE) IN ('1998', '1999') 
	     GROUP BY YEAR(HIRE_DATE), MONTH(HIRE_DATE)
	   ) DS
 GROUP BY MM