Question

I can’t add a not null constraint or remove a default constraint. I would like to add a datetime column to a table and have all the values set to anything (perhaps 1970 or year 2000) but it seems like i cant use not null without a default and I cant remove a default once added in. So how can i add this column? (once again just a plain datetime not null)

Answer 1

Instead of using ALTER TABLE ADD COLUMN, create a new table that has the extra column, and copy your old data. This will free you from the restrictions of ALTER TABLE and let you have a NOT NULL constraint without a default value.

ALTER TABLE YourTable RENAME TO OldTable;
CREATE TABLE YourTable (/* old cols */, NewColumn DATETIME NOT NULL);
INSERT INTO YourTable SELECT *, '2000-01-01 00:00:00' FROM OldTable;
DROP TABLE OldTable;

Edit: The official SQLite documentation for ALTER TABLE now warns against the above procedure because it “might corrupt references to that table in triggers, views, and foreign key constraints.” The safe alternative is to use a temporary name for the new table, like this:

CREATE TABLE NewTable (/* old cols */, NewColumn DATETIME NOT NULL);
INSERT INTO NewTable SELECT *, '2000-01-01 00:00:00' FROM YourTable;
DROP TABLE YourTable;
ALTER TABLE NewTable RENAME TO YourTable;