Question

我的桌子上有两个独特的约束。

CREATE TABLE `targets` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `client` SMALLINT(6) UNSIGNED NOT NULL,
    -- some more fields here
    `order_column` INT(10) NULL DEFAULT NULL,
    PRIMARY KEY (`id`),
    UNIQUE INDEX `client_order_column` (`client`, `order_column`)
)

现在我想更新它，order_column将包含增量整数，从0开始，每个client值。我试图这样做：

replace into targets (
    `id`,
    `client` ,
    `order_column`
) 

(select     
    `id`,
    `client` ,
    0 as order_column from targets
    )
on duplicate key update
    order_column = order_column + 1

但在最后一行获得syntax error。我无法意识到，有什么不对，所以，请帮助我。

顺便说一句：有没有更好的方法来达到预期的效果？

Answer 1

INSERT INTO targets (id, client, order_column) 
SELECT  a.id, a.client , 0 as order_column 
FROM    targets a
        ON DUPLICATE KEY
        UPDATE order_column = a.order_column + 1

INSERT ... ON DUPLICATE KEY UPDATE Syntax

更换INTO ...重复更新密钥更新

1 个答案: