跨多个表聚合的查询

Question

我是 SQL 的新手，我正在尝试创建一个数据库来管理少量库存。这是数据库的结构：

DatabaseStructure

我需要创建一个查询 returns 每个 material 的总库存。因此，第一步是查找与 material 关联的所有批次。其次，查找与每个批次相关的所有动作。然后，将与每个移动相关联的数量相加，但是取决于移动类型（如果是好收据是加法（+），但如果是库存提取是减法（- )).

这是一个包含示例数据和所需结果的表格示例。

Table Material

MaterialID	MaterialDescription
1	Bottle
2	Box

Table 批量

BatchID	MaterialID	VendorMaterial	VendorBatch	ExpirationDate
1000	1	2096027	00123456	12/12/2025
1001	1	2096027	00987654	11/11/2026
1002	2	102400	202400E	10/10/2023

Table 移动

MovementID	BatchID	MovementType	Quantity	CreatedBy	CreatedOnDate
1	1000	Good receipt	100	user1@email.com	4/10/2022
2	1000	Inventory withdrawal	20	user2@email.com	4/15/2022
3	1000	Inventory withdrawal	25	user3@email.com	4/17/2022
4	1001	Good receipt	100	user1@email.com	4/20/2022
5	1001	Inventory withdrawal	10	user4@email.com	4/26/2022
6	1002	Good receipt	50	user1@email.com	2/26/2022

预期查询结果 - 每个 material 的总库存：

MaterialDescription	TotalInventory
Bottle	145
Box	50

TotalInventory 计算：对于 Bottle 有两个 100 的良好收货移动和三个 20、25 和 10 的提款。因此，总库存将为 (100 +100)-(20+25+10)=145.

感谢您的帮助！

Answer 1

select
    mat.MaterialDescription,
    sum(
        case mov.MovementType
            when 'Good receipt' then 1
            when 'Inventory withdrawal' then -1
            else 0 /* don't know what to do for other MovementTypes */
        end * mov.Quantity
    ) as TotalInventory
from
    Material as mat
    left join Batch as bat on bat.MaterialID = mat.MaterialID
    left join Movement as mov on mov.BatchID = bat.BatchID
group by
    mat.MaterialDescription
;

跨多个表聚合的查询

Query to aggregate across multiple tables

sql

tsql

sql-server

azure-sql-database