SQLite Forum

Here are 2 ideas.

Using an [AFTER INSERT trigger](https://sqlite.org/lang_createtrigger.html) (note the use of `INT PRIMARY KEY` instead of `INTEGER PRIMARY KEY`):

```bash
sqlite> CREATE TABLE t1(
   ...>   id INT PRIMARY KEY
   ...> );
sqlite>
sqlite> CREATE TRIGGER t1_id AFTER INSERT ON t1 BEGIN
   ...>   UPDATE t1 SET id = rowid-1 WHERE rowid = new.rowid;
   ...> END;
sqlite>
sqlite> INSERT INTO t1 VALUES(NULL);
sqlite> INSERT INTO t1 VALUES(NULL);
sqlite> INSERT INTO t1 VALUES(NULL);
sqlite>
sqlite> SELECT * FROM t1;
+----+
| id |
+----+
| 0  |
| 1  |
| 2  |
+----+
```

Using [generated columns](https://www.sqlite.org/gencol.html):

```bash
sqlite> CREATE TABLE t2(
   ...>   pk INTEGER PRIMARY KEY,
   ...>   id INT GENERATED ALWAYS AS (pk-1) STORED UNIQUE
   ...> );
sqlite>
sqlite> INSERT INTO t2 VALUES(NULL);
sqlite> INSERT INTO t2 VALUES(NULL);
sqlite> INSERT INTO t2 VALUES(NULL);
sqlite>
sqlite> SELECT * FROM t2;
+----+----+
| pk | id |
+----+----+
| 1  | 0  |
| 2  | 1  |
| 3  | 2  |
+----+----+
```