做一個更新不知道ID

我有這樣的要求：做一個更新不知道ID

UPDATE PEOPLE SET ID_STATE = 5 WHERE ID_STATE IN (3,4);

我會提出同樣的要求，但如果我不知道ID_STATE但只是labelStatePeople

SELECT ID_STATE FROM STATE_PEOPLE WHERE labelStatePeople = 'blue';

實例：

$1 = SELECT ID_STATE FROM STATE_PEOPLE WHERE labelStatePeople = 'blue'; 
$2 = SELECT ID_STATE FROM STATE_PEOPLE WHERE labelStatePeople = 'yellow'; 
$3 = SELECT ID_STATE FROM STATE_PEOPLE WHERE labelStatePeople = 'red';

最後的請求：UPDATE PEOPLE SET ID_STATE = $1 WHERE ID_STATE IN ($2,$3);

來源

2016-05-30 Mercer

只要有一個子查詢，返回那些陌生的人們的ID_STATE值：

UPDATE PEOPLE 
    SET ID_STATE = 5 
WHERE ID_STATE IN (SELECT ID_STATE FROM STATE_PEOPLE 
        WHERE labelStatePeople = 'strange' 
        and ID_STATE IS NOT NULL)

（子查詢的ID_STATE IS NOT NULL部分可以，如果該列是NOT NULL刪除）

來源

2016-05-30 09:16:36 jarlh

我更新了我的文章，以更好地理解我的問題 – Mercer

出於好奇，是否出於性能原因需要「不是NULL」？（假設該列可以爲NULL） – kamilk

@kamilk，不，原因是如果子qeury返回NULL，則WHERE子句將爲false，並且根本不會更新任何行 - 即使子qury也是返回有效的ID_STATE值。（非常常見的錯誤） – jarlh

試試這個

UPDATE PEOPLE 
SET ID_STATE = 5 
WHERE ID_STATE 
IN (SELECT ID_STATE FROM STATE_PEOPLE 
WHERE labelStatePeople 
IN ('blue','yellow','red') 
AND ID_STATE IS NOT NULL);

來源

2016-05-30 09:28:08 JYoThI

做一個更新不知道ID

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