SQL结果按月分组

使用：

  SELECt SUM(CASE WHEN p.problem_type = 'IN' THEN 1 ELSE 0 END) AS IN,          SUM(CASE WHEN p.problem_type = 'OUT' THEN 1 ELSE 0 END) AS OUT,          TO_CHAr(datetime, 'YYYY') AS year,         TO_CHAr(datetime, 'MM') AS month    FROM PROBLEM p   WHERe p.DateTime >= TO_DATE('2010-01-01', 'YYYY-MM-DD')      AND p.DateTime < TO_DATE('2010-01-31', 'YYYY-MM-DD') GROUP BY TO_CHAr(datetime, 'YYYY'), TO_CHAr(datetime, 'MM')

您还可以使用：

  SELECt SUM(CASE WHEN p.problem_type = 'IN' THEN 1 ELSE 0 END) AS IN,          SUM(CASE WHEN p.problem_type = 'OUT' THEN 1 ELSE 0 END) AS OUT,          TO_CHAr(datetime, 'MM-YYYY') AS mon_year    FROM PROBLEM p   WHERe p.DateTime >= TO_DATE('2010-01-01', 'YYYY-MM-DD')      AND p.DateTime < TO_DATE('2010-01-31', 'YYYY-MM-DD') GROUP BY TO_CHAr(datetime, 'MM-YYYY')