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新增外鍵時(shí)報(bào)錯(cuò):
錯(cuò)誤代碼: 1215 Cannot add foreign key constraint
表key_list:
CREATE TABLE key_list
(server_app_id
INT(11) NOT NULL , server_name
CHAR(13) NOT NULL ,
PRIMARY KEY (server_app_id
)
) ENGINE=INNODB DEFAULT CHARSET=utf8
表for_list:
CREATE TABLE for_list
(for_id
INT(11) NOT NULL,for_name
CHAR(13) NOT NULL,
PRIMARY KEY (for_id
)
) ENGINE=INNODB DEFAULT CHARSET=utf8
在表key_list中新增外鍵server_app_id_ibfk:
ALTER TABLE key_list
ADD CONSTRAINT server_app_id_ibfk
FOREIGN KEY (server_app_id
) REFERENCES for_list
(for_id
);
執(zhí)行正常
在表key_list中新增外鍵server_name_id_ibfk:
ALTER TABLE key_list
ADD CONSTRAINT server_name_id_ibfk
FOREIGN KEY (server_name
) REFERENCES for_list
(for_name
);
執(zhí)行報(bào)錯(cuò)。錯(cuò)誤代碼: 1215 Cannot add foreign key constraint
原因:
在新增外鍵時(shí),關(guān)聯(lián)表(for_list)中的相關(guān)字段(for_name)必須為index
解決:
for_list表for_name字段新增索引
ALTER TABLE for_list ADD INDEX for_index_name(for_name);
再次執(zhí)行新增外鍵操作:
ALTER TABLE key_list
ADD CONSTRAINT server_name_id_ibfk
FOREIGN KEY (server_name
) REFERENCES for_list
(for_name
);
發(fā)現(xiàn)操作成功:
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