外键sql oracle

Question

i'm having trouble adding a foreign key to my table. Any suggestions would be amazing, thanks :) the errors i am getting are below

DROP TABLE Table_One
/

CREATE TABLE Table_One
(
col1 number(10),
col2 varchar(200),
PRIMARY KEY(col1)
)

/
DROP TABLE Table_Two
/

CREATE TABLE Table_Two
(
col3 number(10), 
col2 varchar(200),
PRIMARY KEY(col3),
CONSTRAINT fk_col2 FOREIGN KEY(col2) references Table_One(col2)
)
/

SQL> start newtest.sql

Table dropped.


Table created.

DROP TABLE Table_Two * ERROR at line 1: ORA-00942: table or view does not exist

CONSTRAINT fk_col2 FOREIGN KEY(col2) references Table_One(col2)
                                                      *

ERROR at line 6: ORA-02270: no matching unique or primary key for this column-list

Answer 1

The error on the DROP TABLE is because the table doesn't exist yet. The second error is because you have defined col1 as the primary key of Table_One , not col2 , and a foreign key can only reference a primary or unique key. So, either you need to reference col1 or you need to create a unique key on col2 .