创建外键时出现MySQL错误1064

Question

我使用MySQL WorkBench创建的

ALTER TABLE `android_marketplace`.`ban_utilizator` 
DROP INDEX  ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC);
ALTER TABLE `android_marketplace`.`ban_utilizator` 
ADD CONSTRAINT `ban_utilizator_id_utilizator`
 FOREIGN KEY (`id_utilizator`)
 REFERENCES `android_marketplace`.`utilizatori` (`id_utilizator`)
 ON DELETE NO ACTION
 ON UPDATE NO ACTION;

我得到这个：

Operation failed: There was an error while applying the SQL script to the 
database.
Executing:
ALTER TABLE `android_marketplace`.`ban_utilizator` 
DROP INDEX  ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC);
ALTER TABLE `android_marketplace`.`ban_utilizator` 
ADD CONSTRAINT `ban_utilizator_id_utilizator`
 FOREIGN KEY (`id_utilizator`)
 REFERENCES `android_marketplace`.`utilizatori` (`id_utilizator`)
 ON DELETE NO ACTION
 ON UPDATE NO ACTION;

ERROR 1064: You have an error in your SQL syntax; check the manual that 
corresponds to your MariaDB server version for the right syntax to use near '
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC)' at line 2
SQL Statement:
ALTER TABLE `android_marketplace`.`ban_utilizator` 
DROP INDEX  ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC)

Answer 1

该错误与外键无关。

您必须命名要删除的索引。

语法错误消息包括问题的上下文。 如果语法错误显示：

检查...以在'ADD INDEX ban_utilizator_id_utilizator_idx （ id_utilizator ASC）附近使用正确的语法

这意味着该语法希望在您提供ADD INDEX的位置找到其他内容。

在这种情况下，期望您尝试在紧邻ADD INDEX的子句中删除的索引的名称。