Question

我正在开发数据库，并且在此问题中使用了2个特定的表，分别是图稿（ArtworkID，价格，PurchaseID）和购买（PurchaseID，总计）

我想将具有相同Artwork.PurchaseID的艺术品的Artwork.Price加在一起（尽管我希望程序能够在同一查询中总计所有PurchaseID）。

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然后我希望将相加后的价格放入相应的Purchase.PurchaseID行下的Purchase.Total中

我已经尝试了多种方法，但是据推测在第3行上我一直遇到SQL语法错误，我尝试将Artwork更改为Purchase，但还是得到了。我对Joins相当陌生，所以我不确定该怎么做。下面是我开发的代码：

UPDATE Purchase
SET Purchase.Total = SUM(Artwork.Price)
FROM Artwork
INNER JOIN Artwork ON Purchase.PurchaseID = Artwork.PurchaseID
WHERE Artwork.PurchaseID = 'D4758';

结果应将Purchase.Total从NULL更改为购买ID为'D4758'的Artwork.Price的十进制（5,2）SUM值。

我反而得到了错误

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM Artwork INNER JOIN Artwork ON Purchase.PurchaseID = Artwork.PurchaseID WH' at line 3

Answer 1

已解决：

UPDATE Purchase
    SET Total = (SELECT sum(Price)
                 FROM Artwork
                 WHERE Purchase.PurchaseID = Artwork.PurchaseID
                )
 WHERE Purchase.PurchaseID = 'D4758'

Answer 2

您需要在连接发生后写set关键字。还要删除FROM关键字。

UPDATE Purchase as p
INNER JOIN Artwork as a ON p.PurchaseID = a.PurchaseID
SET p.Total = SUM(a.Price)
WHERE a.PurchaseID = 'D4758';

Answer 3

您的FROM子句必须指向您要更新的表（购买），然后指向相关表（艺术品）进行JOIN，因此您的查询应为：

UPDATE
  Purchase
SET
  Purchase.Total = SUM(Artwork.Price)
FROM
  Purchase
INNER JOIN
  Artwork 
ON 
  Purchase.PurchaseID = Artwork.PurchaseID
WHERE
  Artwork.PurchaseID = 'D4758';

Answer 4

您的查询基于SQL Server的更新语法，您在更新后立即编写SET语句。在mysql中，您应该在末尾写SET语句。

UPDATE 
  Purchase pr
INNER JOIN 
  Artwork ar
ON 
  pr.PurchaseID = ar.PurchaseID
SET 
  pr.Total = SUM(ar.Price)
WHERE 
  ar.PurchaseID = 'D4758'

在mySQL中设置的语法为

UPDATE [LOW_PRIORITY] [IGNORE] table_references
SET assignment_list
[WHERE where_condition]

Answer 5

您可以为此使用Task，但是您想在子查询中计算UPDATE。我建议：

SUM()

Answer 6

尝试一下：

UPDATE Purchase as P
INNER JOIN Artwork as A ON P.PurchaseID = A.PurchaseID
SET P.Total = SUM(A.Price)
WHERE A.PurchaseID = 'D4758';

在update query中，您不使用FROM关键字。

如何在联接两个表时解决FROM中的错误语法错误？

6 个答案: