About Mysql:error 1022 (23000): Can ' t write; Duplicate key in table ' Test4 '

ERROR 1022 (23000): Can ' t write; Duplicate key in table ' test4 ': when setting a foreign key for the "test4" table . the foreign key name and the existing foreign key name are duplicated ; The code is as follows , Note the Bold section

Error code :

Mysql> CREATE TABLE Test4 (

ID int,

Cp_name varchar (32),

-Constraint TEST_FK foreign Key (cp_name) references student (name)

);

ERROR 1022 (23000): Can ' t write; Duplicate key in table ' Test4 '

Correct code :

Mysql> CREATE TABLE Test4 (

ID int,

Cp_name varchar (32),

-Constraint TEST1_FK foreign Key (cp_name) references student (name)

);

Query OK, 0 rows affected (0.54 sec)

About Mysql:error 1022 (23000): Can ' t write; duplicate key in table ' Test4 '