MySQL更新多個連接不工作

Question

我想跟隨更新查詢連接，但它不會更新匹配行。

UPDATE table1 T1 
INNER JOIN table2 T2 ON T2.id=10 
INNER JOIN table3 T3 ON T3.category_id=T2.category_id 
SET T1.value=T3.value 
WHERE T1.id=T3.id 

是否支持使用嵌套連接更新查詢？

Answer 1

UPDATE table1 T1 
SET T1.value=T3.value 
INNER JOIN table2 T2 ON T2.id=10 
INNER JOIN table3 T3 ON T3.category_id=T2.category_id 
WHERE T1.id=T3.id 

Answer 2

我很想說你的查詢應該可以工作。但是，也許MySQL不喜歡你的第二行的連接條件與table1沒什麼關係？

以下工作？

UPDATE table1 T1 
    INNER JOIN table3 T3 ON T3.id = T1.id 
    INNER JOIN table2 T2 ON T2.category_id = T3.category_id 
SET T1.value = T3.value 
WHERE T2.id = 10 

Answer 3

這將是更ususal地看到，查詢這樣寫......

UPDATE table1 T1 
    JOIN table3 T3 
    ON t3.id = t1.id 
    JOIN table2 T2 
    ON T2.category_id = T3.category_id 
    SET T1.value = T3.value 
WHERE T2.id=10;