複雜SQL選擇語句

Question

我正在嘗試創建一個執行以下操作的SQL語句，但顯然會失敗。

選擇來自它基於下面的準則的視圖和過濾器的所有信息：

1. 如果給定的字段「CUSTOMER_NUMBER」存在於表格中的任何點
2. 然後檢查內的任何重複最近30天
3. 然後輸出按客戶編號分組的所有不同customer_numbers
4. 有一個計數，以便我可以看到一個項目重複了多少次。

所以今天使用作爲我們當前的日期說，我在我的表中的下列數據項：

customer_number, date 
111111, 2013-01-01 
111111, 2013-05-05 
222222, 2013-01-07 
222222, 2013-03-19 
333333, 2013-05-15 
333333, 2013-05-30 

我希望我的SELECT語句返回如下：

customer_number, date, count 
111111, 2013-01-01, 2 
333333, 2013-05-15, 2 

而且客戶222222將不會顯示，因爲他在過去30天內沒有出現。

這裏是關於我試圖弄清楚這一點。它僅返回當前月份的數據。

SELECT *, COUNT(customer_number) 
FROM red_flags 
WHERE dealer_id = '75' AND date BETWEEN CURDATE() - INTERVAL 30 DAY AND CURDATE() 
GROUP BY customer_number 
HAVING COUNT(customer_number) > 1 

我已經融化我的大腦試圖找出如何或者如果這甚至有可能做一個查詢任何幫助將不勝感激！

Answer 1

這裏是如何做到這一點使用JOIN

select r.customer_number, count(*) ct, min(date) minDate 
from red_flags r 
join (select distinct customer_number 
     from red_flags 
     where dealer_id = '75' 
     and date between CURDATE() - INTERVAL 30 DAY and CURDATE()) x 
ON r.customer_number = x.customer_number 
group by customer_number 
HAVING ct > 1 

SQLFIDDLE

Answer 2

像這樣的東西應該適合你 - 它使用子查詢來找出哪些客戶在過去30天內被標記過。然後它使用COUNT獲得總數，並使用MIN獲得第一個日期。

SELECT customer_number, COUNT(1), MIN(date) minDate 
FROM red_flags 
WHERE customer_number IN (
    SELECT customer_number 
    FROM red_flags 
    WHERE dealer_id = '75' 
     AND date BETWEEN CURDATE() - INTERVAL 30 DAY AND CURDATE() 
) 
GROUP BY customer_number 

如果你只關心那些有多個記錄，你可以添加HAVING子句。

• SQL Fiddle Demo

BTW，使用BETWEEN的日期要小心。我更喜歡明確地使用> =和< =來獲得更多控制。

---

編輯 - 也許是最簡單的解決方案，使用次數與CASE：

SELECT customer_number, COUNT(1), MIN(date) minDate 
FROM red_flags 
GROUP BY customer_number 
HAVING COUNT(CASE WHEN date BETWEEN CURDATE() - INTERVAL 30 DAY AND CURDATE() THEN 1 END) > 0 

• More Fiddle