加入兩個表+第三個表作爲條件列

Question

如果我有三個表，分別爲warehouse，warehouse_order和表warehouse_fulfillment。倉庫順序由倉庫管理員創建的，最初具有0履行記錄，可以有很多warehouse_fulfillment記錄和故障/拒絕的狀態，只有一個成功的狀態（它的工作）：

-- Warehouse 
+---------------------------------------+-----------+----------+ 
| id         | name  | location | 
+---------------------------------------+-----------+----------+ 
| 9bcae08e-ad36-4d97-b9ec-4857714e902a | "big"  | "MLB" | 
+---------------------------------------+-----------+----------+ 
| b442e783-4725-41e9-af83-f75004ee1b38 | "bigger" | "MLB" | 
+---------------------------------------+-----------+----------+ 
| 986d5aa9-0523-42d8-b183-dfd546d3e682 | "biggest" | "MLB" | 
+---------------------------------------+-----------+----------+ 


-- Warehouse_order Table 
+---------------------------------------+--------------------------------------+--------+----------+ 
| id         | warehouse_id       | type | quantity | 
+---------------------------------------+--------------------------------------+--------+----------+ 
| 9cb99fd9-9e5e-4240-8162-d28747be01cd | b442e783-4725-41e9-af83-f75004ee1b38 | BN_100 | 100  | 
+---------------------------------------+-------------------------------------+--------+-----------+ 
| eceb0b5a-5afa-40e4-ac62-efb686e3bdae | 9bcae08e-ad36-4d97-b9ec-4857714e902a | BN_200 | 400  | 
+---------------------------------------+--------------------------------------+--------+----------+ 
| 13370467-cf0c-47f2-8fea-a215500607e6 | 986d5aa9-0523-42d8-b183-dfd546d3e68 | BN_300 | 10  | 
+---------------------------------------+--------------------------------------+--------+----------+ 


-- Warhouse_fulfillment Table 
+---------------------------------------+---------------------------------------+------------+ 
| id         | order_id        | status  | 
+---------------------------------------+---------------------------------------+------------+ 
| 8a69edde-2346-48b8-96d0-6c4e25527f38 | 9cb99fd9-9e5e-4240-8162-d28747be01cd | "FAILLED" | 
+---------------------------------------+---------------------------------------+------------+ 
| a2006a64-9bdc-4bfa-ba14-a44769aeb4a2 | 9cb99fd9-9e5e-4240-8162-d28747be01cd | "REJECTED" | 
+---------------------------------------+---------------------------------------+------------+ 
| bf0aa1fc-6dfc-4fd0-ba20-be101b1985d1 | 9cb99fd9-9e5e-4240-8162-d28747be01cd | "FAILED" | 
+---------------------------------------+---------------------------------------+------------+ 
| 48c7d747-2f9b-4535-8f27-210a43cf5c30 | 9cb99fd9-9e5e-4240-8162-d28747be01cd | "SUCCESS" | 
+---------------------------------------+---------------------------------------+------------+ 
| 7f8e18c9-4322-428a-9370-9ecd1c5ef286 | 13370467-cf0c-47f2-8fea-a215500607e6 | "FAILED" | 
+---------------------------------------+---------------------------------------+------------+ 

我要查詢上述記錄以這樣一種方式，結果看起來像這樣：

+--------------------------------------+-----------+----------+---------------------------------------+------------+----------------+--------------------------------------+ 
| id         | name  | location | order_id        | order_type | order_quantity | fulfillment_id      | 
+--------------------------------------+-----------+----------+---------------------------------------+------------+----------------+--------------------------------------+ 
| 9bcae08e-ad36-4d97-b9ec-4857714e902a | "big"  | "MLB" | eceb0b5a-5afa-40e4-ac62-efb686e3bdae | "BN_100" | 100   | NULL         | 
+--------------------------------------+-----------+----------+---------------------------------------+------------+----------------+--------------------------------------+ 
| b442e783-4725-41e9-af83-f75004ee1b38 | "bigger" | "MLB" | 9cb99fd9-9e5e-4240-8162-d28747be01cd | "BN_200" | 400   | 48c7d747-2f9b-4535-8f27-210a43cf5c30 | 
+--------------------------------------+-----------+----------+---------------------------------------+------------+----------------+--------------------------------------+ 
| 986d5aa9-0523-42d8-b183-dfd546d3e682 | "biggest" | "MLB" | 13370467-cf0c-47f2-8fea-a215500607e6 | "BN_300" | 10    | NULL         | 
+--------------------------------------+-----------+----------+---------------------------------------+------------+----------------+--------------------------------------+ 

我不能沒有在一個訂單有多次失敗的狀態情況下，重複行做到這一點。

Answer 1

你試過SELECT DISTINCT了嗎？因爲您沒有選擇列表中的狀態列（這會導致重複），所以這應該起作用。

SELECT DISTINCT W.id, W.name, W.location, WO.id order_id, WO.type order_type, WO.quantity order_quantity, WF.id fulfillment_id 
FROM warehouse W 
    LEFT JOIN warehouse_order WO ON W.id = WO.warehouse_id 
    LEFT JOIN warehouse_fulfillment WF on WF.order_id = WO.id 

否則，我需要知道DBMS的SQL是，但每次我使用過的味道有一些方法來排序/順序結果與某個分區，這樣，你可以採取只基於第一條記錄在一些關鍵，例如：

SELECT id, name, location, order_id, order_type, order_quantity 
FROM (
    SELECT W.id, W.name, W.location, WO.id order_id, WO.type order_type, WO.quantity order_quantity, WF.id fulfillment_id, ROW_NUMBER() OVER (PARTITION BY WO.id ORDER BY WF.ID) rNum 
FROM warehouse W 
    LEFT JOIN warehouse_order WO ON W.id = WO.warehouse_id 
    LEFT JOIN warehouse_fulfillment WF on WF.order_id = WO.id 
) A 
WHERE rNum = 1 

這將是更好的命令按日期DESC或類似的東西，以獲得最新的記錄。

Answer 2

如果在履行表中沒有一些可靠的方法來確定「最新狀態」，例如時間戳，則需要選擇一些任意方法以在可能的狀態值中獲得優先順序。以下我在over clause中使用了case expression，因此如果某個訂單的狀態存在，則「成功」將獲得行號1。如果您認爲適合該列的其他可能值，請調整大小寫表達式。

當包含行號的子查詢連接到主查詢時，連接包括and rn=1，因此每個訂單隻有履行行是可能的。

請注意，在示例數據中有一個缺少的倉庫行，所以我不得不使用一個左連接，但我希望它是一個內連接在真正的分貝。

SQL Fiddle Demo

CREATE TABLE Warehouse 
    (ID varchar(36), Name varchar(9), Location varchar(5)) 
; 

INSERT INTO Warehouse 
    ("id", "name", "location") 
VALUES 
    ('9bcae08e-ad36-4d97-b9ec-4857714e902a', 'big', 'MLB'), 
    ('b442e783-4725-41e9-af83-f75004ee1b38', 'bigger', 'MLB'), 
    ('986d5aa9-0523-42d8-b183-dfd546d3e682', 'biggest', 'MLB') 
; 


CREATE TABLE Warehouse_order 
    (ID varchar(36), Warehouse_id varchar(36), type varchar(6), quantity int) 
; 

INSERT INTO Warehouse_order 
    ("id", "warehouse_id", "type", "quantity") 
VALUES 
    ('9cb99fd9-9e5e-4240-8162-d28747be01cd', 'b442e783-4725-41e9-af83-f75004ee1b38', 'BN_100', 100), 
    ('eceb0b5a-5afa-40e4-ac62-efb686e3bdae', '9bcae08e-ad36-4d97-b9ec-4857714e902a', 'BN_200', 400), 
    ('13370467-cf0c-47f2-8fea-a215500607e6', '986d5aa9-0523-42d8-b183-dfd546d3e68', 'BN_300', 10) 
; 


CREATE TABLE Warehouse_fulfillment 
    (ID varchar(36), Order_id varchar(36), Status varchar(10)) 
; 


INSERT INTO Warehouse_fulfillment 
    ("id", "order_id", "status") 
VALUES 
    ('8a69edde-2346-48b8-96d0-6c4e25527f38', '9cb99fd9-9e5e-4240-8162-d28747be01cd', 'FAILLED'), 
    ('a2006a64-9bdc-4bfa-ba14-a44769aeb4a2', '9cb99fd9-9e5e-4240-8162-d28747be01cd', 'REJECTED'), 
    ('bf0aa1fc-6dfc-4fd0-ba20-be101b1985d1', '9cb99fd9-9e5e-4240-8162-d28747be01cd', 'FAILED'), 
    ('48c7d747-2f9b-4535-8f27-210a43cf5c30', '9cb99fd9-9e5e-4240-8162-d28747be01cd', 'SUCCESS'), 
    ('7f8e18c9-4322-428a-9370-9ecd1c5ef286', '13370467-cf0c-47f2-8fea-a215500607e6', 'FAILED') 
; 

查詢1：

select 
    o.*, w.name, s.status, s.rn 
from Warehouse_order o 
left join Warehouse w on o.Warehouse_id = w.id 
left join (
     select id, order_id, status 
      , row_number() over(partition by order_id 
           order by case when status = 'SUCCESS' then 1 
              when status = 'FAILED' then 2 
              when status = 'REJECTED' then 3 
              else 4 end) as rn 
     from Warehouse_fulfillment 
    ) s on o.id = s.Order_id and rn=1 

Results：

|         id |       warehouse_id | type | quantity | name | status |  rn | 
|--------------------------------------|--------------------------------------|--------|----------|--------|---------|--------| 
| eceb0b5a-5afa-40e4-ac62-efb686e3bdae | 9bcae08e-ad36-4d97-b9ec-4857714e902a | BN_200 |  400 | big | (null) | (null) | 
| 9cb99fd9-9e5e-4240-8162-d28747be01cd | b442e783-4725-41e9-af83-f75004ee1b38 | BN_100 |  100 | bigger | SUCCESS |  1 | 
| 13370467-cf0c-47f2-8fea-a215500607e6 | 986d5aa9-0523-42d8-b183-dfd546d3e68 | BN_300 |  10 | (null) | FAILED |  1 | 

Answer 3

我不是這個完全肯定，但它聽起來LIK Ë你只是想在order_fulfillment表左連接與「成功」狀態的連接：

select 
    w.id, w.name, w.location, 
    o.id as order_id, o.type as order_type, 
    o.quantity as order_quantity, 
    f.id as fulfillment_id 
from 
    warehouse w 
    join warehouse_order o on 
    w.id = o.warehouse_id 
    left join warhouse_fulfillment f on 
    o.id = f.order_id and 
    f.status = 'SUCCESS' 

你似乎由於不關心非成功的記錄，並有保證，有僅會成爲'SUCCESS'的履行記錄，這應該避免任何重複。