Oracle 按月、年、按年、月排序

Question

我正在尝试在 Oracle 中编写一个查询，该查询将按月和年对日期进行分组，然后将它们整齐地排序。 除此之外，月份必须显示它的名称而不是它的月份编号。

我目前的查询是：

SELECT to_char(datumgeleend, 'MONTH') as "Maand geleend", 
to_char(datumgeleend, 'YYYY') as "Jaar geleend", SUM(bedrag)
FROM lening
GROUP BY to_char(datumgeleend, 'MONTH'), to_char(datumgeleend, 'YYYY')
ORDER BY to_char(datumgeleend, 'YYYY'), to_char(datumgeleend, 'MONTH') DESC;

问题是顺序按月份的第一个字母而不是月份的数字。

所以我想修正一下，我将查询稍微调整为：

SELECT to_char(datumgeleend, 'MONTH') as "Maand geleend", 
to_char(datumgeleend, 'YYYY') as "Jaar geleend", SUM(bedrag)
FROM lening
GROUP BY to_char(datumgeleend, 'MONTH'), to_char(datumgeleend, 'YYYY')
ORDER BY to_char(datumgeleend, 'YYYY'), extract(month from datumgeleend) 
DESC;

不幸的是，这个查询产生了以下错误：

ORA-00979: not a GROUP BY expression

Answer 1

只需在 group by 子句中添加extract(month from datumgeleend)：

SELECT to_char(datumgeleend, 'MONTH') as "Maand geleend", 
to_char(datumgeleend, 'YYYY') as "Jaar geleend", SUM(bedrag)
FROM lening
GROUP BY to_char(datumgeleend, 'MONTH'), to_char(datumgeleend, 'YYYY'), extract(month from datumgeleend)
ORDER BY to_char(datumgeleend, 'YYYY'), extract(month from datumgeleend) DESC;

Answer 2

一个简单的解决方法，使用 WITH factoring 子句，附加列（必须包含在 GROUP BY 子句中）用于根据需要对数据进行排序）：

WITH temp AS (
  SELECT
    TO_CHAR(datumgeleend,'MONTH') AS maand_geleend,
    TO_CHAR(datumgeleend,'YYYY') AS jaar_geleend,
    SUM(bedrag) sum_bedrag,
   --
    TO_CHAR(datumgeleend,'yyyymm') yyyymm
  FROM
    lening
  GROUP BY
    TO_CHAR(datumgeleend,'MONTH'),
    TO_CHAR(datumgeleend,'YYYY'),
    TO_CHAR(datumgeleend,'yyyymm')
) SELECT
  maand_geleend,
  jaar_geleend,
  sum_bedrag
  FROM
  temp
ORDER BY
  yyyymm DESC;