不存在数据时显示月份值

Question

我使用 SQL Server，并且我编写了以下 SQL 查询，以便显示客户名称、城镇名称、产品、销售数量、销售年份、销售月份和经销商名称以及我在特定月份销售的数量，但是即使一个月没有数据，我也希望查询按月显示。

SELECT dbo.Customerdetl.cust_name, dbo.Towndetl.town_name, dbo.productdetl.prod_desc, dbo.SalesSummary.sales_qty, dbo.SalesSummary.year_numb, dbo.SalesSummary.month_numb,dbo.DistributorDetl.DISTNAME
FROM     dbo.SalesSummary INNER JOIN
                  dbo.productdetl ON dbo.SalesSummary.ProductCode = dbo.productdetl.ProductCode INNER JOIN
                  dbo.DistributorDetl ON dbo.SalesSummary.DistCode = dbo.DistributorDetl.DistCode INNER JOIN
                  dbo.Customerdetl ON dbo.SalesSummary.cust_code = dbo.Customerdetl.cust_code INNER JOIN
                  dbo.Towndetl ON dbo.SalesSummary.town_code = dbo.Towndetl.town_code  
WHERE  (dbo.SalesSummary.year_numb = 2021) AND (dbo.Customerdetl.cust_name = N'Janani Pharmacy') AND (dbo.productdetl.prod_desc = N'Mycotin')

我得到的结果是：

Cust_name	Town	Product	Sales_qty	Year	Month	Distributor_name
Janani Pharmacy	HANWELLA	Mycotin	10	2021	7	NEGA
Janani Pharmacy	HANWELLA	Mycotin	10	2021	4	NEGA

我想得到的是：

Cust_name	Town	Product	Sales_qty	Year	Month	Distributor_name
Janani Pharmacy	HANWELLA	Mycotin	0	2021	1	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	2	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	3	NEGA
Janani Pharmacy	HANWELLA	Mycotin	10	2021	4	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	5	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	6	NEGA
Janani Pharmacy	HANWELLA	Mycotin	10	2021	7	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	8	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	9	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	10	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	11	NEGA
Janani Pharmacy	HANWELLA	Mycotin	0	2021	12	NEGA

我也尝试过使用左连接，但它不起作用。

Answer 1

我猜 Sales 表没有保存没有销售的记录。这样的东西在“理论上”应该构建一个包含你需要的一切的表。

1. TABLENEEDS 获取所有不同的年份、distcode、productcode、town_code 和 cust_code
2. BUILDOUT 运行交叉连接，将所有月份应用于 TABLENEEDS 中的所有不同集（假设 dbo.SalesSummary.month_numb 包含所有 12 个月）
3. ADDSALESBACK 正是这样做的，它是跨所有条件的左连接，将不存在销售额的空值变为零。

最终的选择只显示 ADDSALESBACK - 您只需从 ADDSALESBACK 表而不是 dbo.SalesSummary 进行其他联接

WITH TABLENEEDS AS (
SELECT DISTINCT
  dbo.SalesSummary.year_numb,
  dbo.SalesSummary.DistCode,
  dbo.SalesSummary.ProductCode,
  dbo.SalesSummary.town_code,
  dbo.SalesSummary.cust_code,
FROM dbo.SalesSummary
)

,

BUILDOUT AS(
SELECT *
FROM TABLENEEDS
CROSS JOIN (SELECT DISTINCT dbo.SalesSummary.month_numb FROM dbo.SalesSummary) AS MONTHSFORBUILDOUT
)

,

ADDSALESBACK AS(
SELECT
BUILDOUT.*,
COALESCE(dbo.SalesSummary.sales_qty, 0) AS sales_qty
FROM BUILDOUT
LEFT JOIN dbo.SalesSummary
ON dbo.SalesSummary.year_numb = BUILDOUT.year_numb AND dbo.SalesSummary.DistCode = BUILDOUT.DistCode AND dbo.SalesSummary.ProductCode, = BUILDOUT.ProductCode AND dbo.SalesSummary.town_code = BUILDOUT.town_code AND dbo.SalesSummary.cust_code = BUILDOUT.cust_code AND 
dbo.SalesSummer.month_numb = BUILDOUT.month_numb)

SELECT *
FROM ADDSALESBACK