sql DROP CONSTRAINT UNIQUE不起作用 [英] sql DROP CONSTRAINT UNIQUE not working

问题描述

我得到了下表:

CREATE TABLE `unsub_counts` (
 `count_id` int(11) NOT NULL AUTO_INCREMENT,
 `unsub_date` date DEFAULT NULL,
 `unsub_count` int(11) DEFAULT NULL,
 `store_id` smallint(5) DEFAULT NULL,
 PRIMARY KEY (`count_id`),
 UNIQUE KEY `uc_unsub_date` (`unsub_date`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

其中列unsub_date是unique.现在，我想放弃这种唯一性，因为我需要在unsub_date + store_id上具有唯一索引.

where column unsub_date is unique. Now I want to drop that uniqueness, because I need to have a unique index on unsub_date + store_id.

我在网上找到了建议，但失败了:

I found suggestions on the net, but is failing:

ALTER TABLE `unsub_counts` DROP CONSTRAINT `unsub_date`

给我:您的SQL语法有误；检查与您的MySQL服务器版本相对应的手册以获取正确的语法，以在第1行的'CONSTRAINT unsub_date'附近使用

gives me: 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 'CONSTRAINT unsub_date' at line 1

这与MyISAM有关吗?还有其他建议吗?

Is this related to MyISAM? Any other suggestions?

推荐答案

对约束名称使用drop index:

ALTER TABLE unsub_counts DROP INDEX uc_unsub_date;

或者只是:

drop index uc_unsub_date on unsub_counts;

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