如何将SQL结果存储为变量，并在PostgreSQL的后续SQL命令中使用它

Question

I'm trying to catch the first day of current month:

select date_trunc('month',  (CURRENT_DATE - INTERVAL '1 day')::date)

and intend to use it in a subsequent SQL command as an variable start_date, like:

select * from table where create_time > start_date;

How to implement that in PostgreSQL? Thanks!

Answer 1

with start_date as (
    select date_trunc('month', current_date) as start_date
)
select *
from
    t
    cross join
    start_date
where create_time >= start_date