Question

我需要更新某些表的记录，并且尝试使用以下命令：

UPDATE auction a        
JOIN (SELECT bidding_price, user_id, auction_id FROM bid_account WHERE auction_id = a.auctionID ORDER BY bidpack_buy_date DESC LIMIT 1) ult_lance_a
SET a.auc_final_price=ult_lance_a.bidding_price, a.buy_user=ult_lance_a.user_id
WHERE a.auctionID=ult_lance_a.auction_id;

但是我遇到以下错误：

#1054 - Column 'a.auctionID' unknown in 'where clause'

我做错了什么？

以下是命令的返回：SELECT bidding_price, user_id, auction_id FROM bid_account WHERE auction_id = XXX ORDER BY bidpack_buy_date DESC LIMIT 1

投标价格= 6.23
用户ID = 1720
拍卖ID = 1818

在auction表中，有以下列：

auc_final_price
bidding_price
拍卖ID

有几条记录，但列的记录相同： auction_id 和 auctionID 。

我需要的只是获取bid_account表中输入的LAST值，然后将值复制到auction表中。

Answer 1

也许有一种更好的措辞来表达您的更新，但是，如果您要使用相关的子查询，则可能需要将它们直接放入UPDATE auction a SET auc_final_price = (SELECT bidding_price FROM bid_account WHERE auction_id = a.auctionID ORDER BY bidpack_buy_date DESC LIMIT 1), buy_user = (SELECT user_id FROM bid_account WHERE auction_id = a.auctionID ORDER BY bidpack_buy_date DESC LIMIT 1);子句中：

CREATE TEMPORARY TABLE IF NOT EXISTS 
    auctionView ( INDEX(auction_id) ) 
    ENGINE=MyISAM 
AS (
    SELECT b1.auction_id, b1.bidding_price, b1.user_id
    FROM bid_account b1
    INNER JOIN
    (
        SELECT auction_id, MAX(bidpack_buy_date) AS max_buy_date
        FROM bid_account
        GROUP BY auction_id
    ) b2
        ON b1.auction_id = b2.auction_id AND b1.bidpack_buy_date = b2.max_buy_date
);

UPDATE auction a
INNER JOIN auctionView b
    ON b.auction_id = a.auctionID
SET
    a.auc_final_price = b.bidding_price,
    a.buy_user = b.user_id;

实际上，我认为我们仍然可以使用更新联接语法编写您的查询。由于您的表很大，因此您可以尝试加入一个临时表（代替一个有关系的视图）：

qa03

Answer 2

您的主要问题是您在联接中缺少“ ON”子句，并尝试使用子查询的“ WHERE”子句来完成相同的事情。

a.auctionID在子查询SELECT bidding_price, user_id, auction_id FROM bid_account WHERE auction_id = a.auctionID ...的上下文中不存在，因此将引发错误。

尝试这样：

UPDATE 
    auction AS a
INNER JOIN 
    /* Find the highest (max) bidpack_buy_date for each auction */
    (SELECT MAX(bidpack_buy_date) AS `Max Date`, auction_id FROM bid_account GROUP BY auction_id) AS maxdates
    ON 
    maxdates.auction_id = a.auctionID
INNER JOIN
    /* The data from bid_acount that accompanies the max dates found above */
    bid_account AS ult_lance_a
    ON
    ult_lance_a.bidpack_buy_date = maxdates.`Max Date`
    AND
    ult_lance_a.auction_id = maxdates.auction_ID
SET 
    a.auc_final_price = ult_lance_a.bidding_price,
    a.buy_user = ult_lance_a.user_id

我用来设置测试的代码：

DROP TABLE IF EXISTS bid_account;
CREATE TABLE IF NOT EXISTS bid_account (
    auction_id int,
    user_id int, 
    bidding_price numeric(8,2),
    bidpack_buy_date DATETIME
);

DROP TABLE IF EXISTS auction;
CREATE TABLE IF NOT EXISTS auction (
    auctionID int,
    buy_user int,
    auc_final_price numeric(8,2)
);

INSERT INTO 
    bid_account 
        (auction_id, user_id, bidding_price, bidpack_buy_date)
    VALUES
        (1,1, 10.00, '2017-01-01 12:00:01 PM'),
        (1,2, 20.00, '2017-01-01 12:00:02 PM'),
        (1,3, 30.00, '2017-01-01 12:00:03 PM'),
        (1,4, 40.00, '2017-01-01 12:00:04 PM'),
        (2,1, 10.00, '2017-01-01 12:00:01 PM'),
        (2,2, 20.00, '2017-01-01 12:00:02 PM'),
        (2,3, 30.00, '2017-01-01 12:00:03 PM');

INSERT INTO 
    auction 
        (auctionID)
    VALUES
        (1),
        (2),
        (3),
        (4),
        (5),
        (6),
        (7);

使用现有数据进行命令更新

2 个答案: