SQL 错误 #1071 - 指定的键太长；最大密钥长度为 767 字节 [英] SQL Error #1071 - Specified key was too long; max key length is 767 bytes

问题描述

CREATE TABLE wp_locations (
        `id` INT(11) NOT NULL AUTO_INCREMENT,
        `city` VARCHAR(255) NOT NULL,
        `name` VARCHAR(255) NOT NULL,
        CONSTRAINT `city_name` UNIQUE (`city`, `name`)
    ) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

我收到一个 sql 错误 '#1071 - 指定的键太长；最大密钥长度为 767 字节'

I got an sql error '#1071 - Specified key was too long; max key length is 767 bytes'

我做错了什么?

推荐答案

MySQL 总是为 UTF8 字段保留最大数量，它是 4 个字节，所以 255 + 255使用您的 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;您已超过 767 个最大密钥长度限制.

MySQL always reserves the max amount for a UTF8 field which is 4 bytes so with 255 + 255 with your DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; you are over the 767 max key length limit.

您只能减少单个 varchar 长度或不使用复合键.

You can only reduce the single varchar length or don't use a composite key.

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