SQL+ Oracal Support PK AND FK

[1nstan7]

Well Did I do w3schoolhelp and overclock Right?

CREATE TABLE W3schoolhelp (aircraft_code CHAR(5) primary key,HTML CHAR(20),);CREATE TABLE Overclock_test(purchase_order_no NUMBER(3) primary key,coding CHAR(4) not null,PC INT(4),CONSTRAINT f_coding  FOREIGN KEY (coding}REFERENCES coder(coding)  );

I'm not sure if I did the caps or if I missed anything?Also if you look at stackoverflow_help it has overclocking which is a primary key and a Forgien? How do I do that?Anyway all help is appreciated!

 

[justsomeguy]

The column names in the diagram don't match the SQL statements. I don't see much of a reason to have something be both a primary and a foreign key. If it is a primary key that means it's unique in the table. If it's a foreign key that means it's also in another table. If you have unique data like that then it can all go in one table.