如何在更新查询中设置两列的总和

Question

**

  

如何在更新查询中设置两列的总和

**

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

一种可行的方法是使用不同的别名引用同一个表并加入它们：

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'