How do I add a foreign key to an existing SQLite table?

Question

I have the following table:

CREATE TABLE child( 
  id INTEGER PRIMARY KEY, 
  parent_id INTEGER, 
  description TEXT);

How do I add a forei

Answer 1

You can add the constraint if you alter table and add the column that uses the constraint.

First, create table without the parent_id:

CREATE TABLE child( 
  id INTEGER PRIMARY KEY,  
  description TEXT);

Then, alter table:

ALTER TABLE child ADD COLUMN parent_id INTEGER REFERENCES parent(id);