如何更新查詢中設置了兩列求和

Question

**

如何更新詢問

**

INSERT INTO account (id, cid, stock, stockAvailable, sumStock) VALUES (1, '1','10', '20', '0'), (2,'1', '10', '20', '0'); 

    UPDATE account SET sumStock=SUM(stock) FROM account where cid= '1' 

Answer 1

一種可能的方式來設置的兩列求和這是通過參考具有不同別名的同一表並加入它們：

UPDATE account AS a1 INNER JOIN ( SELECT SUM(stock) AS count FROM account ) AS a2 ON a1.cid = a2.cid SET a1.sumStock=a2.count WHERE a1.cid= '1'