Specified key was too long; max key length is 3072 bytes

sql是这样的：

CREATE TABLE `dal_product` ( /*产品表*/
    `pid` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    `main_iid` VARCHAR(1024) COMMENT "主图片",
    `cid` INT NOT NULL COMMENT "品类ID",
    `name` VARCHAR(512) COMMENT "产品名称",
    `desc` VARCHAR(4096) COMMENT "产品描述",
    `shelf_time` DATETIME COMMENT "上架时间",
    `sold_count` INT COMMENT "卖出数量",
    `available_count` INT COMMENT "剩余数量",
    `is_onsale` TINYINT COMMENT "0下架 1在售",
    FOREIGN KEY (`cid`) REFERENCES `dal_class`(`cid`) ON UPDATE CASCADE ON DELETE RESTRICT,
    FOREIGN KEY (`main_iid`) REFERENCES `dal_product_img`(`iid`) ON UPDATE CASCADE ON DELETE RESTRICT
);

我就想存这么大的数据 不想改小

谢谢

解决了
原来是外健的类型没有对应上