我有一个表，它的主键在其他几个表中使用，并且有几个外键到其他表。

CREATE TABLE location (
   locationID INT NOT NULL AUTO_INCREMENT PRIMARY KEY
   ...
) ENGINE = InnoDB;

CREATE TABLE assignment (
   assignmentID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
   locationID INT NOT NULL,
   FOREIGN KEY locationIDX (locationID) REFERENCES location (locationID)
   ...
) ENGINE = InnoDB;

CREATE TABLE assignmentStuff (
   ...
   assignmentID INT NOT NULL,
   FOREIGN KEY assignmentIDX (assignmentID) REFERENCES assignment (assignmentID)
) ENGINE = InnoDB;

问题是，当我试图删除一个外键列(即locationIDX)它给我一个错误。

"ERROR 1025 (HY000):重命名时出错"

我怎样才能在上面的分配表中删除列而不得到这个错误?