我希望使用另一個表中的數據更新空字段

Question

我使用了SELECT COUNT（*）來檢查我的WHERE語句並獲得了正確數量的更新，但是當我嘗試更新時，我在第3行得到語法錯誤。

UPDATE scans AS s 
SET s.sbjnum = d.sbjnum 
JOIN details AS d on d.name = s.name 
WHERE s.sbjnum ='' 

Answer 1

你必須有一個FROM有一個JOIN

UPDATE scans 
SET sbjnum = d.sbjnum 
FROM scans s 
JOIN details AS d ON d.name = s.name 
WHERE s.sbjnum ='' 

根據MySQL手冊，你可以寫這樣的：

UPDATE scans AS s 
JOIN details AS d ON d.name = s.name 
SET sbjnum = d.sbjnum 
WHERE s.sbjnum =''