Shulou(Shulou.com)06/01 Report--

New foreign key Times error:

Error code: 1215 Cannot add foreign key constraint

Table 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

Table 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

Add the foreign key server_app_id_ibfk to the table key_list:

ALTER TABLE key_list ADD CONSTRAINT server_app_id_ibfk FOREIGN KEY (server_app_id) REFERENCES for_list (for_id)

Execute normally

Add the foreign key server_name_id_ibfk to the table key_list:

ALTER TABLE key_list ADD CONSTRAINT server_name_id_ibfk FOREIGN KEY (server_name) REFERENCES for_list (for_name)

Execute the error report. Error code: 1215 Cannot add foreign key constraint

Reason:

When adding a foreign key, the related field (for_name) in the associated table (for_list) must be index

Resolve:

New index in for_ list table for _ name field

ALTER TABLE for_list ADD INDEX for_index_name (for_name)

Execute the new foreign key operation again:

ALTER TABLE key_list ADD CONSTRAINT server_name_id_ibfk FOREIGN KEY (server_name) REFERENCES for_list (for_name)

The discovery operation was successful:

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