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create table test (a int, b int)
alter table test add c int generated always as (a-b) stored
insert into test (a, b) values (1, 5), (5, 2), (4, 4), (6, 4)
select * from test
| a | b | c |
|---|---|---|
| 1 | 5 | -4 |
| 5 | 2 | 3 |
| 4 | 4 | 0 |
| 6 | 4 | 2 |