Learn the cause and how to resolve the ORA-02270 error message in Oracle.
When you encounter an ORA-02270 error, the following error message will appear:
You tried to reference a table using a unique or primary key, but the columns that you listed did not match the primary key, or a primary key does not exist for this table.
The option(s) to resolve this Oracle error are:
This error commonly occurs when you try to create a foreign key that references a table that doesn't have a primary key. To resolve this problem, create a primary key on the referenced table. Then re-execute your command to create the foreign key.
For example, if you had tried to execute the following commands.
CREATE TABLE supplier ( supplier_id numeric(10) >not null, supplier_name varchar2(50) not null, contact_name varchar2(50) ); CREATE TABLE products ( product_id numeric(10) not null, supplier_id numeric(10) not null, CONSTRAINT fk_supplier FOREIGN KEY (supplier_id) REFERENCES supplier (supplier_id) );
You would receive the following error message:
Since there is no primary key on the supplier table, you can not create a foreign key on the products table that references the supplier table.
You can correct this error by adding a primary key to the supplier table as follows and then re-execute the CREATE TABLE statement for the products table:
ALTER TABLE supplier ADD CONSTRAINT supplier_pk PRIMARY KEY (supplier_id);