Question: Trying to create a table with a foreign key. I keep getting `ORA-00904` error. What am I doing wrong. Is it because table of the foreign key is not yet created ?

```
CREATE TABLE ingredients( 
   ingredient_id       number(2,0),
   ingredient          VARCHAR2(55) NOT NULL,
   quantity_required   VARCHAR2(15) NOT NULL,
   optional_ingredient VARCHAR2(30) NOT NULL,
   CONSTRAINT pk_ingr_id PRIMARY KEY(ingredient_id),
   CONSTRAINT fk_ingredient_list FOREIGN KEY(id) REFERENCES ingredient_list(id)
);

```

Answer: 
Take a look at the following line:

```
CONSTRAINT fk_ingredient_list FOREIGN KEY(id) REFERENCES ingredient_list(id)

```

Your table has no column named "id". I assume you meant to write

```
CONSTRAINT fk_ingredient_list FOREIGN KEY(ingredient_id) REFERENCES ingredient_list(id)

```

EDIT:  

Additionally, as you suspected yourself, if you want to reference the `ingredient_list` table, you must create it before creating the `ingredients` table that references it.
We never know but in my case I had this exception no matter what name I gave my column.
I had a library with EF which pointed on the proper database. The entities were correct.

But on the client part (a web application), the connection string pointed to another database!
A stupid mistake, it was hard to pinpoint this silly misgave....

So please have a look at the connection string FIRST :)