postgresql：将SQL查询的结果存储在变量中

Question

I'm trying to store the result of a sql query, which should be a single date, in a variable. I'm doing this because I plan to reuse the variable several times throughout the rest of the script. I've tried the following:

DO
$$
DECLARE
  date_ordered date;
BEGIN
  date_ordered := SELECT MIN(event_date) FROM event;
END;
$$

Unfortunately I'm getting a syntax error at SELECT . Any idea what I'm doing wrong here or if this is even possible?

Answer 1

Enclose the query in parenthesis.

...
date_ordered := (SELECT MIN(event_date) FROM event);
...

Or use SELECT ... INTO .

...
SELECT MIN(event_date) INTO date_ordered FROM event;
...