# 1
See [this stackoverflow](https://stackoverflow.com/questions/2944499/how-to-add-an-auto-incrementing-primary-key-to-an-existing-table-in-postgresql)

```
ALTER TABLE table_name 
ADD COLUMN id INTEGER PRIMARY KEY GENERATED ALWAYS AS IDENTITY;

ALTER TABLE table_name 
ADD COLUMN id INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY;
```

and the `generate always as identity` it can be done in a `create table`.

# 2
See [[Postgres_Data_Types]].