我有两个表，一个包含生产数据，另一个包含预测数据。我正在加入这两个表格，将实际生产数据与预测数据进行比较。 我的样本表如下：
**Prod Tbl**
Product Plant pmonth pyear quantity
B007 2 January 2014 45
B007 2 February 2014 270
B007 2 March 2014 270
B007 2 April 2014 45
B007 2 May 2014 90
B007 2 May 2014 90
B007 2 June 2014 90
B007 2 June 2014 90
B007 2 July 2014 135
B007 2 July 2014 45
B007 2 August 2014 135
B007 2 August 2014 135
B007 2 July 2015 90
B007 2 August 2014 135
B007 2 September 2014 135
B007 2 September 2015 135
B007 2 October 2015 90
B007 2 September 2014 135
B007 2 September 2014 90
B007 2 September 2014 90
B007 2 November 2014 254
B007 2 May 2016 90
B007 2 August 2016 135
B007 2 October 2016 87
**Forecast Tbl**
Product Plant Fmonth Fyear Fqty
B007 2 July 2017 100
B007 2 August 2017 100
B007 2 September 2017 100
B007 2 October 2017 100
B007 2 Novenmber 2017 100
B007 2 December 2017 100
用于加入的查询：
Select a.Product,
a.plant,
b.pmonth,
b.pyear,
coalesce(b.quantity,0) as quantity,
a.fmonth,
a.fyear,coalesce(a.fqty,0) as fqty
from
Frcast_Tbl as a
left join on Prod_Tbl as b on (a.Product = b.Product
and a.Plant = b.plant
and b.pMonth = a.fMonth);
结果： 加入后
Product Plant Pmonth Pyear Quantity Fmonth Fyear fqty
B007 2 July 2014 180 July 2017 100
B007 2 July 2015 90 July 2017 100
B007 2 August 2014 405 August 2017 100
B007 2 August 2016 315 August 2017 100
B007 2 September 2014 450 September 2017 100
B007 2 September 2015 135 September 2017 100
B007 2 October 2016 177 October 2017 100
B007 2 October 2015 90 October 2017 100
B007 2 November 2014 356 November 2017 100
B007 2 December 2016 90 December 2017 100
B007 2 January 2015 90 January 2018 100
B007 2 January 2016 90 January 2018 100
B007 2 January 2014 45 January 2018 100
B007 2 January 2017 90 January 2018 100
B007 2 February 2014 270 February 2018 99
B007 2 March 2014 270 March 2018 101
B007 2 March 2017 90 March 2018 101
B007 2 April 2014 45 April 2018 100
B007 2 May 2016 90 May 2018 100
B007 2 May 2014 180 May 2018 100
B007 2 May 2017 90 May 2018 100
过滤特定年份以更好地解释问题
Producr plant pmonth pyear quantity fmonth fyear fqty
B007 2 August 2016 315 August 2017 100
B007 2 October 2016 177 October 2017 100
B007 2 December 2016 90 December 2017 100
所需表格
Product Plant Pmonth Pyear Quantity fmonth fyear fqty
B007 2 January 2016 90 null null 0
B007 2 May 2016 90 null null 0
B007 2 June 2016 270 null null 0
B007 2 null null 0 July 2017 100
B007 2 August 2016 315 August 2017 100
B007 2 null null 0 September 2017 100
B007 2 October 2016 177 October 2017 100
B007 2 null null 0 November 2017 100
B007 2 December 2016 90 December 2017 100
我的查询正在做的是它使用左连接加入项目，工厂和月份，但我希望我的结果表显示prod和frcast的所有月份，如果找不到月份，则显示null或0。请帮忙。
答案 0 :(得分：0)
你可以试试这个。 FULL JOIN之后的子查询仅从Products表中提取一年。 我也为ORDER BY添加了一个CASE。
一年版
SELECT COALESCE(a.Product,b.Product) AS PRODUCT,
COALESCE(a.plant,b.plant) AS PLANT,
b.pmonth,
b.pyear,
coalesce(b.quantity,0) as quantity,
a.fmonth AS FMONTH,
a.fyear,
coalesce(a.fqty,0) as fqty
FROM FORECAST A
FULL JOIN (SELECT * FROM PROD WHERE pyear=2016) B on a.Product = b.Product
and a.Plant = b.plant
and A.fmonth = b.pMonth
ORDER BY CASE COALESCE(b.pmonth, a.fmonth)
WHEN 'January' THEN 1
WHEN 'February' THEN 2
WHEN 'March' THEN 3
WHEN 'April' THEN 4
WHEN 'May' THEN 5
WHEN 'June' THEN 6
WHEN 'July' THEN 7
WHEN 'August' THEN 8
WHEN 'September' THEN 9
WHEN 'October' THEN 10
WHEN 'November' THEN 11
WHEN 'December' THEN 12
END ;
请注意您的样本数据（第一张表）不完整。
输出：
+-------------+-------+---------+-------+----------+-----------+-------+------+
| PRODUCT | PLANT | pmonth | pyear | quantity | FMONTH | fyear | fqty |
+-------------+-------+---------+-------+----------+-----------+-------+------+
| B007 | 2 | January | 2016 | 90 | NULL | NULL | 0 |
| B007 | 2 | May | 2016 | 90 | NULL | NULL | 0 |
| B007 | 2 | June | 2016 | 270 | NULL | NULL | 0 |
| B007 | 2 | NULL | NULL | 0 | July | 2017 | 100 |
| B007 | 2 | August | 2016 | 135 | August | 2017 | 100 |
| B007 | 2 | NULL | NULL | 0 | September | 2017 | 100 |
| B007 | 2 | October | 2016 | 87 | October | 2017 | 100 |
| B007 | 2 | NULL | NULL | 0 | November | 2017 | 100 |
| B007 | 2 | NULL | NULL | 0 | December | 2017 | 100 |
+-------------+-------+---------+-------+----------+-----------+-------+------+
已添加：多年版本，在PROD表上有分组依据
SELECT COALESCE(a.Product,b.Product) AS PRODUCT,
COALESCE(a.plant,b.plant) AS PLANT,
b.pmonth,
COALESCE(b.pyear,Y.pyear) AS pyear,
COALESCE(b.quantity,0) as quantity,
a.fmonth AS FMONTH,
a.fyear,
coalesce(a.fqty,0) as fqty
FROM FORECAST A
CROSS JOIN (SELECT DISTINCT pyear FROM PROD /* WHERE pyear IN (2015,2016)*/ ) Y
FULL JOIN (SELECT Product, Plant, pyear, pmonth, SUM(quantity) AS quantity
FROM PROD /*WHERE pyear IN (2015,2016)*/
GROUP BY Product, Plant, pyear, pmonth
) B on a.Product = b.Product
and a.Plant = b.plant
and A.fmonth = b.pMonth
AND Y.pyear= B.pyear
ORDER BY COALESCE(b.pyear,Y.pyear), CASE COALESCE(b.pmonth, a.fmonth)
WHEN 'January' THEN 1
WHEN 'February' THEN 2
WHEN 'March' THEN 3
WHEN 'April' THEN 4
WHEN 'May' THEN 5
WHEN 'June' THEN 6
WHEN 'July' THEN 7
WHEN 'August' THEN 8
WHEN 'September' THEN 9
WHEN 'October' THEN 10
WHEN 'November' THEN 11
WHEN 'December' THEN 12
END ;
输出：
+---------+-------+-----------+-------+----------+-----------+-------+------+
| PRODUCT | PLANT | pmonth | pyear | quantity | FMONTH | fyear | fqty |
+---------+-------+-----------+-------+----------+-----------+-------+------+
| B007 | 2 | January | 2014 | 45 | NULL | NULL | 0 |
| B007 | 2 | February | 2014 | 270 | NULL | NULL | 0 |
| B007 | 2 | March | 2014 | 270 | NULL | NULL | 0 |
| B007 | 2 | April | 2014 | 45 | NULL | NULL | 0 |
| B007 | 2 | May | 2014 | 180 | NULL | NULL | 0 |
| B007 | 2 | June | 2014 | 180 | NULL | NULL | 0 |
| B007 | 2 | July | 2014 | 180 | July | 2017 | 100 |
| B007 | 2 | August | 2014 | 405 | August | 2017 | 100 |
| B007 | 2 | September | 2014 | 450 | September | 2017 | 100 |
| B007 | 2 | NULL | 2014 | 0 | October | 2017 | 100 |
| B007 | 2 | November | 2014 | 254 | November | 2017 | 100 |
| B007 | 2 | NULL | 2014 | 0 | December | 2017 | 100 |
| B007 | 2 | July | 2015 | 90 | July | 2017 | 100 |
| B007 | 2 | NULL | 2015 | 0 | August | 2017 | 100 |
| B007 | 2 | September | 2015 | 135 | September | 2017 | 100 |
| B007 | 2 | October | 2015 | 90 | October | 2017 | 100 |
| B007 | 2 | NULL | 2015 | 0 | November | 2017 | 100 |
| B007 | 2 | NULL | 2015 | 0 | December | 2017 | 100 |
| B007 | 2 | January | 2016 | 90 | NULL | NULL | 0 |
| B007 | 2 | May | 2016 | 90 | NULL | NULL | 0 |
| B007 | 2 | June | 2016 | 270 | NULL | NULL | 0 |
| B007 | 2 | NULL | 2016 | 0 | July | 2017 | 100 |
| B007 | 2 | August | 2016 | 135 | August | 2017 | 100 |
| B007 | 2 | NULL | 2016 | 0 | September | 2017 | 100 |
| B007 | 2 | October | 2016 | 87 | October | 2017 | 100 |
| B007 | 2 | NULL | 2016 | 0 | November | 2017 | 100 |
| B007 | 2 | NULL | 2016 | 0 | December | 2017 | 100 |
+---------+-------+-----------+-------+----------+-----------+-------+------+
答案 1 :(得分：0)
在过滤特定年份的记录时使用FULL OUTER JOIN
Select a.Product,a.plant,b.pmonth,b.pyear,coalesce(b.quantity,0) as quantity,a.fmonth,a.fyear,coalesce(a.fqty,0) as fqty
from Frcast_Tbl as a
FULL OUTER JOIN on Prod_Tbl as b on a.Product = b.Product and
a.Plant = b.plant and
b.pMonth = a.fMonth