如何在mysql的列中找到缺少的月份？

Question

这是我的 view_remit。我需要确定month_paid 列中缺少的月份。

我使用此代码获取此表，但我不知道如何确定缺少的月份。

SELECT RemitNo, PEN, Employer, month_paid, Total_PBR_Amt
FROM view_remit
JOIN (    
        SELECT 'JAN' as month_paid,'2016-01-01' as start,'2016-01-31' as end UNION ALL
        SELECT 'FEB' as month_paid,'2016-02-01' as start,'2016-02-29' as end UNION ALL
        SELECT 'MAR' as month_paid,'2016-03-01' as start,'2016-03-31' as end UNION ALL
        SELECT 'APR' as month_paid,'2016-04-01' as start,'2016-04-30' as end UNION ALL
        SELECT 'MAY' as month_paid,'2016-05-01' as start,'2016-05-31' as end UNION ALL
    SELECT 'JUN' as month_paid,'2016-06-01' as start,'2016-06-30' as end UNION ALL
    SELECT 'JUL' as month_paid,'2016-07-01' as start,'2016-07-31' as end UNION ALL
    SELECT 'AUG' as month_paid,'2016-08-01' as start,'2016-08-31' as end UNION ALL
        SELECT 'SEP' as month_paid,'2016-09-01' as start,'2016-09-30' as end UNION ALL
        SELECT 'OCT' as month_paid,'2016-10-01' as start,'2016-10-31' as end UNION ALL
        SELECT 'NOV' as month_paid,'2016-11-01' as start,'2016-11-30' as end UNION ALL
        SELECT 'DEC' as month_paid,'2016-12-01' as start,'2016-12-31' as end 
    ) M
    ON view_remit.AP_From <= M.end 
   AND view_remit.AP_To >= M.start
ORDER BY PEN, AP_From

我需要得到这个输出。

|PEN|Employer|month|
| 1 |   a    | MAR |
| 1 |   a    | JUN |
| 1 |   a    | JUL |
| 1 |   a    | SEP |
| 1 |   a    | OCT |
| 1 |   a    | NOV |

非常感谢任何帮助。 提前谢谢你。

Answer 1

由于我的声誉等级，我仍然无法发表评论。一旦您回答我的问题，我会立即更正此答案：

• 您能否放置更完整的表格示例：缺少 AP_From 和 AP_To 列。

• 我不明白您如何将 Pen 和雇主列与缺少的月份联系起来。 无论如何，根据您桌子上的可用数据来获取缺失的月份，我将按照以下步骤进行：

-- Just for sample query purpose IF OBJECT_ID('tempdb..#view_remit') is not null DROP TABLE #view_remit CREATE TABLE #view_remit ( RemitNo INT, PEN INT, Employer VARCHAR(10), wmonth VARCHAR(3), Total_PBR_Amt FLOAT, AP_Date DATE ) INSERT INTO #view_remit VALUES (1,1,'a','JAN',200, '2016-01-20'), (1,1,'a','FEV',200, '2016-02-12'), (1,1,'a','APR',200, '2016-04-25'), (1,1,'a','AUG',200, '2016-08-02'), (1,1,'a','DEC',200, '2016-12-24') -- Your working month table IF OBJECT_ID('tempdb..#table_month') is not null DROP TABLE #table_month CREATE TABLE #table_month ( wmonth VARCHAR(3), DateBegin DATE, EndBegin DATE ) INSERT INTO #table_month VALUES ('JAN', '2016-01-01', '2016-01-31'), ('FEV', '2016-02-01', '2016-02-29'), ('MAR', '2016-03-01', '2016-03-31'), ('APR', '2016-04-01', '2016-04-30'), ('MAI', '2016-05-01', '2016-05-31'), ('JUN', '2016-06-01', '2016-06-30'), ('JUL', '2016-07-01', '2016-07-31'), ('AUG', '2016-08-01', '2016-08-31'), ('SET', '2016-09-01', '2016-09-30'), ('OCT', '2016-10-01', '2016-10-31'), ('NOV', '2016-11-01', '2016-11-30'), ('DEC', '2016-12-01', '2016-12-31') SELECT PEN, Employer, tm.wmonth FROM #table_month tm LEFT JOIN #view_remit vr ON vr.wmonth = tm.wmonth WHERE vr.wmonth is null

Answer 2

通常您会为此使用EXCEPT set operator。设置一个名为 months 的表，其中包含所有月份，然后选择所有这些月份除了view_remit 中的那些月份。

select month from months
except
select distinct month from view_remit

但是 MySQL 不支持EXCEPT。相反，请使用 left outer join 来获取不在 view_remit 中的月份。

select distinct months.month
from months
left join view_remit vr on months.month = vr.month
where vr.month is null;