获取一个年份、月份、一段时间的年月份sql，例如从某年到今年的时间段2017-01、2017-02

获取年份

SELECT year
  FROM (    SELECT LPAD (LEVEL, 4, 0) AS year
              FROM DUAL
        CONNECT BY LEVEL <= TO_NUMBER (TO_CHAR (SYSDATE, 'yyyy')))
 WHERE year > 2014;

执行的结果为下图

获取月份

     SELECT LPAD (LEVEL, 2, 0) AS month
      FROM DUAL
CONNECT BY LEVEL < 13;

执行的结果为下图

 

 获取一段时间的年月份

SELECT year || '-' || month AS ym
  FROM (SELECT year
          FROM (    SELECT LPAD (LEVEL, 4, 0) AS year
                      FROM DUAL
                CONNECT BY LEVEL <= TO_NUMBER (TO_CHAR (SYSDATE, 'yyyy')))
         WHERE year > 2014),
       (    SELECT LPAD (LEVEL, 2, 0) AS month
              FROM DUAL
        CONNECT BY LEVEL < 13)
 WHERE 1 = 1

执行的结果为下图