GROUP_CONCAT與加入導致雙記錄

Question

我使用的查詢：

SELECT `customers`.`customers_id`, 
      `customer_name`, 
      GROUP_CONCAT(customer_tags.customer_tag_name ORDER BY customer_tag_name SEPARATOR ', '), 
      '' 
FROM `customers` 
LEFT OUTER JOIN `customer_tags_ids` ON `customer`.`customers_id` = `customer_tags_ids`.`customers_id` 
LEFT OUTER JOIN `customer_tags` ON `customer_tags_ids`.`customer_tags_ids_id` = `customer_tags`.`customer_tags_id` 
WHERE `customers`.`account_id` = 1 
GROUP BY `customers`.`customers_id` 
ORDER BY `customers`.`customers_id` desc, `customers`.`customer_name` asc 

對下面的表

客戶

+-------------+---------------+ 
|customers_id | customer_name| 
+-------------+---------------+ 
|1   | Customer 1 | 
+-------------+---------------+ 
|2   | Customer 2 | 
+-------------+---------------+ 

customer_persons

+-----------+-------------+------------+------------+ 
| persons_id| customers_id| firstname | lastname | 
+-----------+-------------+------------+------------+ 
|1   | 1   | Mehmet  | Yaman  | 
+-----------+-------------+------------+------------+ 
|2   | 1   | Zafer  | Zorlu  | 
+-----------+-------------+------------+------------+ 
|3   | 2   | Serkan  | Eryaman | 
+-----------+-------------+------------+------------+ 
|4   | 2   | Nedim  | Yaman  | 
+-----------+-------------+------------+------------+ 

個

customer_tags

+-------------------+--------------------+ 
|customer_tags_id | customer_tag_name | 
+-------------------+--------------------+ 
|1     | Google   | 
+-------------------+--------------------+ 
|2     | Yahoo    | 
+-------------------+--------------------+ 
|3     | Aol    | 
+-------------------+--------------------+ 
|4     | Facebook   | 
+-------------------+--------------------+ 

customer_tags_ids

+--------------------+------------------+--------------+ 
|customer_tags_ids_id| customer_tags_id| customers_id | 
+--------------------+------------------+--------------+ 
|1     | 1    | 1   | 
+--------------------+------------------+--------------+ 
|2     | 1    | 2   | 
+--------------------+------------------+--------------+ 
|3     | 2    | 1   | 
+--------------------+------------------+--------------+ 
|4     | 2    | 2   | 
+--------------------+------------------+--------------+ 
|5     | 3    | 2   | 
+--------------------+------------------+--------------+ 
|6     | 4    | 2   | 
+--------------------+------------------+--------------+ 

我需要得到的結果：

+-----------+--------------+-----------------------------+----------------+ 
|customer_id|customer_name |firstname + lastname   | customer_tags | 
+-----------+--------------+-----------------------------+----------------+ 
|1   | Customer 1 | Mehmet Yaman, Zafer Zorlu | Google, Yahoo |    
+-----------+--------------+-----------------------------+----------------+ 
|2   | Customer 2 | Serkan Eryaman, Nedim Yaman | Google, Yahoo, | 
|   |    |        | Aol, Facebook | 
+-----------+--------------+-----------------------------+----------------+ 

但是當我使用上面的查詢我得到如下：

| CUSTOMERS_ID | CUSTOMER_NAME |                          CUSTOMERNAME |            CUSTOMERTAGS | 
|--------------|---------------|--------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------| 
|   1 | Customer 1 |                Mehmet Yaman, Zafer Zorlu, Mehmet Yaman, Zafer Zorlu |        Google, Google, Yahoo, Yahoo | 
|   2 | Customer 2 | Serkan Eryaman, Serkan Eryaman, Nedim Yaman, Nedim Yaman, Serkan Eryaman, Serkan Eryaman, Nedim Yaman, Nedim Yaman | Aol, Aol, Facebook, Facebook, Google, Google, Yahoo, Yahoo | 

正如您所看到的客戶名稱和標籤重複。我該如何解決這個問題？

Answer 1

您需要做幾件事才能得到結果。首先，它看起來像customer_tags上的JOIN沒有使用正確的列。你有：

ON `customer_tags_ids`.`customer_tags_ids_id` = `customer_tags`.`customer_tags_id` 

並將您的數據看起來像你需要：

ON `customer_tags_ids`.`customer_tags_id` = `customer_tags`.`customer_tags_id` 

然後因爲你要在多個列使用GROUP_CONCAT，你會串接時需要使用DISTINCT數據：

SELECT 
    c.`customers_id`, 
    c.`customer_name`, 
    GROUP_CONCAT(DISTINCT CONCAT(cp.`firstname`, ' ', cp.`lastname`) SEPARATOR ', ') as CustomerName, 
    GROUP_CONCAT(DISTINCT ct.customer_tag_name ORDER BY ct.customer_tag_name SEPARATOR ', ') as CustomerTags 
FROM `customers` c 
INNER JOIN `customer_persons` cp 
    ON c.`customers_id` = cp.`customers_id` 
LEFT OUTER JOIN `customer_tags_ids` cti 
    ON c.`customers_id` = cti.`customers_id` 
LEFT OUTER JOIN `customer_tags` ct 
    ON cti.`customer_tags_id` = ct.`customer_tags_id` 
-- WHERE c.`customers_id` = 1 
GROUP BY c.`customers_id`, c.`customer_name` 
ORDER BY c.`customers_id`, c.`customer_name` asc; 

請參閱SQL Fiddle with Demo。這得到結果：

| CUSTOMERS_ID | CUSTOMER_NAME |    CUSTOMERNAME |     CUSTOMERTAGS | 
|--------------|---------------|-----------------------------|------------------------------| 
|   1 | Customer 1 | Mehmet Yaman, Zafer Zorlu |    Google, Yahoo | 
|   2 | Customer 2 | Serkan Eryaman, Nedim Yaman | Aol, Facebook, Google, Yahoo |