使用內部連接中的select count（）進行mysql更新

Question

我有以下選擇語句，用於計算值在聯接表中出現的次數：

SELECT table1.idx, count(table1.idx) FROM 
(table2 INNER JOIN table1 ON table1.id=table2.id AND table2.value = 'target') 
GROUP BY table1.idx;

現在，我想用這些結果更新第三個表，將計數設置為table3.idx = table1.idx。 我試過了

UPDATE table3 SET count_col=joined_table.c FROM 
(SELECT table1.idx, count(table1.idx) FROM 
   (table2 INNER JOIN table1 ON table1.id=table2.id AND table2.value = 'target') 
   GROUP BY table1.idx
) joined_table WHERE table3.idx = table1.idx;

如我如何從SQL Server中的SELECT更新中所建議的？ ，也嘗試過

UPDATE table3 SET count_col=(
    SELECT COUNT(table1.idx) 
    FROM (table1 INNER JOIN table2 ON table1.id=table2.id AND table2.value = 'target') 
    GROUP BY table1.idx 
WHERE table3.idx = table1.idx);

按照MySQL的建議-基於SELECT Query的UPDATE查詢 ，但是它們都不起作用。 正確的語法是什么？

Answer 1

UPDATE table3 
JOIN 
(
  SELECT table1.idx, count(table1.idx) as cnt
  FROM table2 
  INNER JOIN table1 ON table1.id = table2.id 
                   AND table2.value = 'target'
  GROUP BY table1.idx
) joined_table ON table3.idx = joined_table.idx
SET count_col = joined_table.cnt