postgresql: use timestamp variable within pl pgsql - postgresql

Question

Im new using pl pgsql. I want to concatenate two variables but im gotting always same error: time_ variable is not known
Let's say that date_ is of type date and time_ is of type time. The error came from this row:
sum(extract(epoch from (least(s.end, gs.date_+time_) - greatest(s.beg, gs.date_))) / 60) as Timing
My code is below
delcare
time_ time;
Begin
execute $$SELECT CURRENT_TIMESTAMP::time FROM $$||result_table INTO time_;
execute $$SELECT MAX(date_) FROM $$||result_table INTO max_date;
IF max_date is not NULL THEN
execute $$DELETE FROM $$||result_table||$$ WHERE date_ >= $$||quote_literal(max_date);
ELSE
max_date := 'XXXXXXX';
end if;
execute $$
INSERT INTO $$result_table$$
(Id, gs.date_, TIME, timing)
SELECT * from (
select
Id, gs.date_,
(case
When TRIM(set) ~ '^OPT[0-9]{3}/MINUTE/$'
Then 'minute'
When TRIM(set) ~ '^OPT[0-9]{3}/SECOND/$'
Then 'second' as TIME,
sum(extract(epoch from (least(s.end, gs.date_+time_) -
greatest(s.beg, gs.date_)
)
) / 60) as Timing
from source s cross join lateral
generate_series(date_trunc('day', s.beg), date_trunc('day',
least(s.end,
CASE WHEN $$||quote_literal(max_date)||$$ = 'XXXXXXX'
THEN (current_date)
ELSE $$||quote_literal(max_date)||$$
END)
), interval '1 day') gs(date_)
where ( (beg, end) overlaps ($$||quote_literal(max_date)||$$'00:00:00', $$||quote_literal(max_date)||$$'23:59:59'))
group by id, gs.date_, TIME
) as X
where ($$||quote_literal(max_date)||$$ = X.date_ and $$||quote_literal(max_date)||$$ != 'XXXXXXX')
OR ($$||quote_literal(max_date)||$$ ='XXXXXXX')

Answer 1

Dynamic SQL should be generated through format() and parameters should not be passed as string literals, but through placeholders and using.
Your code is really hard to read, incomplete and there are some substantial syntax errors which stem from e.g. a missing END for the CASE and parentheses not properly paired. So the following code might still contain some errors as I apparently have no way of testing it.
But as your main SELECT does not seem to use dynamic SQL at all, all the quote_literal() and string concatenation is unnecessary, just use the variables directly.
As max_date is supposed to be a date value you can assign the string 'XXXXX' to it, but if you use the max_date directly, you can get rid of that check as far as I can tell.
declare
time_ time;
max_date date;
result_table text := 'contract_frequency';
table_schema text := 'public';
Begin
time_ := localtime;
execute format('SELECT MAX(date_) FROM %I.%I', table_schema, result_table) into INTO max_date;
IF max_date is not NULL THEN
execute format('DELETE FROM %I.%I WHERE date_ >= $1', table_schema, result_table) using max_date;
ELSE
-- you replace XXXX with current_date in the CASE expression
-- later on, so using current_date here seems the right thing to do
max_date := current_date;
end if;
SELECT *
from (
select
Id, gs.date_,
case
When TRIM(set) ~ '^OPT[0-9]{3}/MINUTE/$' Then 'minute'
When TRIM(set) ~ '^OPT[0-9]{3}/SECOND/$' Then 'second' as TIME,
end
sum(extract(epoch from (least(s.end, gs.date_+time_) - greatest(s.beg, gs.date_) ) ) / 60) as Timing
from source s
cross join lateral
generate_series(date_trunc('day', s.beg), date_trunc('day', least(s.end, max_date)), interval '1 day') gs(date_)
where (beg, end) overlaps (max_date::timestamp, max_date + time '23:59:59')
group by id, gs.date_, TIME
) as X
where (max_date = X.date_ and max_date <> current_date)
OR (max_date = current_date)
end;