[英]MAX() OVER PARTITION BY in Oracle SQL
我正在嘗試利用 MAX() OVER PARTITION BY 函數來評估我公司購買的特定零件的最新收據。 以下是去年的幾個部分的信息示例表:
| VEND_NUM | VEND_NAME | RECEIPT_NUM | RECEIPT_ITEM | RECEIPT_DATE |
|----------|--------------|-------------|----------|--------------|
| 100 | SmallTech | 2001 | 5844HAJ | 11/22/2017 |
| 100 | SmallTech | 3188 | 5521LRO | 12/31/2017 |
| 200 | RealSolution | 5109 | 8715JUI | 05/01/2017 |
| 100 | SmallTech | 3232 | 8715JUI | 11/01/2017 |
| 200 | RealSolution | 2101 | 4715TEN | 01/01/2017 |
如您所見,第三行和第四行顯示了相同部件號的兩個不同供應商。
這是我當前的查詢:
WITH
-- various other subqueries above...
AllData AS
(
SELECT VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM, RECEIPT_DATE
FROM tblVend
INNER JOIN tblReceipt ON VEND_NUM = RECEIPT_VEND_NUM
WHERE
VEND_NUM = '100' OR VEND_NUM = '200' AND RECEIPT_DATE >= '01-Jan-2017'
),
SELECT MAX(RECEIPT_DATE) OVER PARTITION BY(RECEIPT_ITEM) AS "Recent Date", RECEIPT_ITEM
FROM AllData
我的返回集如下所示:
| Recent Date | RECEIPT_ITEM |
|-------------|--------------|
| 11/22/2017 | 5844HAJ |
| 12/31/2017 | 5521LRO |
| 11/01/2017 | 8715JUI |
| 11/01/2017 | 8715JUI |
| 01/01/2017 | 4715TEN |
但是,它應該如下所示:
| Recent Date | RECEIPT_ITEM |
|-------------|--------------|
| 11/22/2017 | 5844HAJ |
| 12/31/2017 | 5521LRO |
| 11/01/2017 | 8715JUI |
| 01/01/2017 | 4715TEN |
任何人都可以就我做錯了什么提供建議嗎? 看起來它只是在替換最近的日期,而不是只給我我想要的最近的行。
最終,我希望我的桌子看起來像這樣。 但是,我不知道如何正確使用 MAX() 或 MAX() OVER PARTITION BY() 函數來實現這一點:
| VEND_NUM | VEND_NAME | RECEIPT_NUM | RECEIPT_ITEM | RECEIPT_DATE |
|----------|--------------|-------------|----------|--------------|
| 100 | SmallTech | 2001 | 5844HAJ | 11/22/2017 |
| 100 | SmallTech | 3188 | 5521LRO | 12/31/2017 |
| 100 | SmallTech | 3232 | 8715JUI | 11/01/2017 |
| 200 | RealSolution | 2101 | 4715TEN | 01/01/2017 |
使用窗口函數ROW_NUMBER() OVER (PARTITION BY receipt_item ORDER BY receipt_date DESC)
為每一行分配一個序列號。 具有最近receipt_date
的receipt_item
行將編號為1。
WITH
-- various other subqueries above...
AllData AS
(
SELECT VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM, RECEIPT_DATE,
ROW_NUMBER() OVER (PARTITION BY RECEIPT_ITEM ORDER BY RECEIPT_DATE DESC ) AS RN
FROM tblVend
INNER JOIN tblReceipt ON VEND_NUM = RECEIPT_VEND_NUM
WHERE
VEND_NUM IN ( '100','200') AND RECEIPT_DATE >= '01-Jan-2017'
)
SELECT VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM, RECEIPT_DATE
FROM AllData WHERE RN = 1
我在這里看到幾個問題。 一,使用聚合函數MAX()
作為分析函數(Oracle 有用地稱之為窗口函數)的語法如下所示:
MAX(receipt_date) OVER ( PARTITION BY receipt_item )
(注意括號的位置)。 其次,從你想要的結果集中,你實際上並不想要一個窗口函數,你想要聚合。 窗口(或解析)函數將始終為其分區中的每一行返回一行; 這就是它的工作方式。 所以我想你想要的是這個:
WITH
-- various other subqueries above...
AllData AS
(
SELECT VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM, RECEIPT_DATE
FROM tblVend
INNER JOIN tblReceipt ON VEND_NUM = RECEIPT_VEND_NUM
WHERE ( VEND_NUM = '100' OR VEND_NUM = '200' ) AND RECEIPT_DATE >= DATE'2017-01-01'
)
SELECT VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM, MAX(RECEIPT_DATE)
FROM AllData
GROUP BY VEND_NUM, VEND_NAME, RECEIPT_NUM, RECEIPT_ITEM;
現在我對上面的內容做了一些小的更改,例如在OR
條件周圍加上括號(使用IN ('100','200')
可能會更好),因為AND
優先於OR
(因此您的查詢會在以下位置獲得結果) VEND_NUM = '100' OR ( VEND_NUM = '200' RECEIPT_DATE >= DATE'2017-01-01' )
...但也許這就是你想要的?)。
只是路過,但我認為您必須將日期格式化為“YYYY-MM-DD”格式,以便它不考慮“時間”。
這回答了問題的原始版本。
您的where
子句可能看起來像這樣:
WHERE VEND_NUM IN ('100', '200') AND RECEIPT_DATE >= DATE '2017-01-01'
您想要的很可能只是:
SELECT DISTINCT RECEIPT_DATE, RECEIPT_ITEM
FROM tblVend INNER JOIN
tblReceipt
ON VEND_NUM = RECEIPT_VEND_NUM
WHERE VEND_NUM IN ('100', '200') AND RECEIPT_DATE >= DATE '2017-01-01';
至少,這會返回您想要返回的內容。
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