將SELECT語句轉換爲其對應的UPDATE語句

Question

我有一個SQL查詢來計算我需要使用UPDATE語句更新其信息的確切數量。但它包含一些複雜的連接，我不確定如何在UPDATE語句中重新創建該語句。任何幫助？

我的查詢是在這裏：

select distinct c.id 
from implementation.tt_ngma_exclude_emails nee 
join customer c on nee.util_account_id = c.util_internal_id 
join customer_notification_contact cnc on cnc.customer_id = c.id 
left join customer_notification_contact_audit cnca on cnca.customer_id = c.id 
where cnc.changed_on = '2015-11-15 12:30:02'; 

的這裏的目標是在customer_notification_contact表更新特定領域，而不是從我選擇的實施表。我想設置email領域的數控工作臺爲NULL到處是cnc.customer_id = c.id

這裏是我的嘗試，但它似乎並沒有工作：

UPDATE customer_notification_contact cnc 
(select distinct cnc.customer_id opower_customer_id 
from implementation.tt_ngma_exclude_emails nee 
join customer c on nee.util_account_id = c.util_internal_id 
join customer_notification_contact cnc on cnc.customer_id = c.id 
where cnc.changed_on = '2015-11-15 12:30:02' 
) T2 
SET cnc.email = NULL 
WHERE cnc.customer_id = T2.opower_customer_id; 

Answer 1

請這給一試只需將T1.SOME_COLUMN（最後第2行）替換爲您要更新的實際列名即可。我添加了GROUP BY CNC.CUSTOMER_ID，因爲當您更新多行時，您應該知道該計數屬於哪個客戶。除非你試圖用相同的計數更新所有的行，我假設你沒有試圖去做。

UPDATE customer_notification_contact T1, 
(
select count(distinct c.id) AS MY_COUNT,CNC.CUSTOMER_ID 
from implementation.tt_ngma_exclude_emails nee 
join customer c on nee.util_account_id = c.util_internal_id 
join customer_notification_contact cnc on cnc.customer_id = c.id 
left join customer_notification_contact_audit cnca on cnca.customer_id = c.id 
where cnc.changed_on = '2015-11-15 12:30:02' 
GROUP BY CNC.CUSTOMER_ID 
)T2 
SET T1.SOME_COLUMN = T2.MY_COUNT 
WHERE T1.CUSTOMER_ID = T2.CUSTOMER_ID 

UPDATE看到更新後的問題，這應該是查詢。

UPDATE customer_notification_contact T1, 
(
select distinct c.id 
    from implementation.tt_ngma_exclude_emails nee 
    join customer c on nee.util_account_id = c.util_internal_id 
    join customer_notification_contact cnc on cnc.customer_id = c.id 
    left join customer_notification_contact_audit cnca on cnca.customer_id = c.id 
    where cnc.changed_on = '2015-11-15 12:30:02' 
)T2 
SET T1.EMAIL = NULL 
WHERE T1.CUSTOMER_ID = T2.id