Projection with a field creates from another field

CREATE PROJECTION
AS SELECT
    CASE WHEN (sysdate() - login_ts) % randomint(7) = 5
...

daniel=> create table calendar ("date" date not null, "year" int default year("date"), "month" int default month("date"), "day" int default day("date")); CREATE TABLE daniel=> copy calendar(date) from stdin direct; Enter data to be copied followed by a newline. End with a backslash and a period on a line by itself. >> 2000-01-01 >> 2000-01-02 >> 2000-01-03 >>\ \ .                                     --- PARSER ((( daniel=> select * from calendar ;     date    | year | month | day  ------------+------+-------+-----  2000-01-01 | 2000 |     1 |   1  2000-01-02 | 2000 |     1 |   2  2000-01-03 | 2000 |     1 |   3 (3 rows)