I am am building a Time Dimension table in PostgreSQL with DATE_ID and DATE_DESC.
My T-SQL (works perfectly) script is:
set DATEFIRST 1
;WITH DATES AS (
SELECT CAST('2019-01-01 00:00:00.000' AS datetime) AS [DATE]
UNION ALL
SELECT DATEADD(HH,1,[DATE])
FROM DATES
WHERE DATEADD(HH,1,[DATE]) <= CAST('2019-12-31' AS datetime)
)
SELECT
DATE_ID, DATE_DESC
from
(
SELECT
CONVERT(int, CONVERT(char(8), DATE, 112)) AS DATE_ID,
DATE AS DATE_DESC
FROM
DATES)a
order by 1
OPTION (MAXRECURSION 0)
At the moment Im trying to convert this code to PostgreSQL readable one and it does not work..
Here is mine at the moment:
set EXTRACT(DOW FROM TIMESTAMP '2019-01-01 00:00:00.000')+1
;WITH DATES AS (
SELECT CAST('2019-01-01 00:00:00.000' AS timestamp) AS DATE
UNION ALL
SELECT CURRENT_DATE + INTERVAL '1 hour'
FROM DATES
WHERE CURRENT_DATE + INTERVAL '1 hour' <= CAST('2019-12-31' AS timestamp)
)
SELECT DATE_ID, DATE_DESC from
(SELECT cast(to_char((DATE)::TIMESTAMP,'yyyymmddhhmiss') as BIGInt) AS DATE_ID,
DATE AS DATE_DESC
FROM
DATES)a
order by 1
OPTION (MAXRECURSION 0)
I need all the hours (24h) between 2019-01-01 and 2019-12-31 . At the moment I think OPTION (MAXRECURSION 0) and set EXTRACT(DOW FROM TIMESTAMP '2019-01-01 00:00:00.000')+1 is not working properly.
Its a problem of Recursive CTE, In Postgresql, your desired query will be like below
WITH recursive DATES AS (
SELECT CAST('2019-01-01 00:00:00.000' AS timestamp) AS date_
UNION ALL
SELECT date_ + INTERVAL '1 hour'
FROM DATES
WHERE date_ + INTERVAL '1 hour' <= CAST('2019-12-31' AS timestamp)
)
SELECT DATE_ID, DATE_DESC from
(SELECT cast(to_char((date_)::TIMESTAMP,'yyyymmddhhmiss') as BIGInt) AS DATE_ID,
date_ AS DATE_DESC
FROM
DATES)a
order by 1
DEMO
Related
I need to generate series of date till current_date based on job's last run date
last run date ='2022-10-01'
current date = '2022-10-05'
generate date like
varchar dynamic_date = '2022-10-01','2022-10-02','2022-10-03','2022-10-04','2022-10-05'
and pass to where to clause
select *
from t1
where created_date in (dynamic_date)
this is not allowed as dynamic_date is varchar and created_date is date column
trying to find efficient way to do this
You can use generate_series()
select *
from t1
where created_date in (select g.dt::date
from generate_series(date '2022-10-01',
current_date,
interval '1 day') as g(dt)
)
Or even simpler:
select *
from t1
where created_date >= date '2022-10-01'
and created_date <= current_date
I want to compute certain statistics montly in a postgres database
WITH RECURSIVE totals(start, t_end, null_count, not_null_count) AS (
VALUES (date_trunc('month', current_date + interval '1 month'),
date_trunc('month', current_date + interval '2 months'),
0::bigint)
UNION
SELECT start - interval '1 month' as start, start as t_end,
(SELECT count(*) filter (WHERE flag IS NULL) FROM tbl
WHERE created_at >= start
and created_at < t_end
and deleted_at < current_timestamp
) as null_count,
(SELECT count(*) filter (WHERE flag IS NOT NULL) FROM tbl
WHERE created_at >= start
and created_at < t_end
and deleted_at < current_timestamp
) as not_null_count
FROM totals
WHERE start > current_date - interval '1 year'
)
select * from totals
This would give me what I want, but would scan tbl twice.
Is there a way to to this scanning only once, like one would do in a plain query
SELECT count(*) filter (WHERE flag IS NULL) null_count,
count(*) filter (WHERE flag IS NOT NULL) not_null_count, FROM tbl
WHERE created_at >= start
AND created_at < t_end
AND deleted_at < current_timestamp
I know I could group by date_trunk('month', created_at) but doing that causes the query to sort the rows, and this is very costly in this case.
Yes. You can update your query to -
WITH RECURSIVE totals(start, t_end, null_count, not_null_count) AS (
VALUES (date_trunc('month', current_date + interval '1 month'),
date_trunc('month', current_date + interval '2 months'),
0::bigint)
UNION
SELECT start - interval '1 month' as start, start as t_end,
count(*) filter (WHERE flag IS NULL) as null_count,
count(*) filter (WHERE flag IS NOT NULL) as not_null_count
FROM tbl
JOIN totals ON created_at >= start
and created_at < t_end
WHERE start > current_date - interval '1 year'
AND deleted_at < current_timestamp
)
select * from totals
I need to get first day of each five days of month using posgrees. For example if no is 2.03 then I would get 1.03. If today would be 19.03 then I would get 15.03. I tried to use following if statements but for today;s day I got null and I'm not sure why. Also there surely is some less complicated way to do this operation. Any ideas?
create or replace function getFirstDayOfFive()
returns timestamp with time zone as $$
declare
firstDay timestamp;
begin
if (now()::date>date_trunc('month', now()::date) and now()::date < date_trunc('month', now()::date) + interval '5 day') then
return firstDay = date_trunc('month', now()::date);
elsif (now()::date>date_trunc('month', now()::date) + interval '5 day' and now()::date < date_trunc('month', now()::date) + interval '10 day') then
return firstDay = (date_trunc('month', now()::date) + interval '5 day')::date;
elsif (now()::date>date_trunc('month', now()::date) + interval '10 day' and now()::date < date_trunc('month', now()::date) + interval '15 day') then
return firstDay = (date_trunc('month', now()::date) + interval '10 day')::date;
elsif (now()::date>date_trunc('month', now()::date) + interval '15 day' and now()::date < date_trunc('month', now()::date) + interval '20 day') then
return firstDay = (date_trunc('month', now()::date) + interval '15 day')::date;
elsif (now()::date>date_trunc('month', now()::date) + interval '20 day' and now()::date < date_trunc('month', now()::date) + interval '25 day') then
return firstDay = (date_trunc('month', now()::date) + interval '20 day')::date;
end if;
end;
$$
language plpgsql;
demo:db<>fiddle
SELECT
make_date( -- 4
date_part('year', my_date)::int, -- 3
date_part('month', my_date)::int,
greatest( -- 2
floor(date_part('day', my_date) / 5) * 5, -- 1
1
)::int
)
Get day of the current date using date_part(). After it round it to full multiple 5 with floor(day / 5) * 5
The provided algorithm always gives the previous multiple of 5 (for 19 it gives 15, for 6 it gives 5, ...). However, for days 1 to 4 it gives 0. So this is an exception which needs to be handled. This is done here
Get year and month part of the current date
Create the expected date.
This query can be embedded into a function, of course:
create or replace function getFirstDayOfFive()
returns timestamp with time zone as $$
declare
firstDay timestamp;
begin
SELECT
make_date(
date_part('year', now())::int,
date_part('month', now())::int,
greatest(
floor(date_part('day', now()) / 5) * 5,
1
)::int
)
INTO firstDay;
RETURN firstDay;
end;
$$
language plpgsql;
Edit: From the comments: Same for Last Day:
You have to change:
floor() to ceil()
the greatest(..., 1) into least(..., last day of current month)
To get the last date of the current month, you have to find the first day using date_trunc('month', ...), add one month to get the first day of the next month and subtract one day from it:
demo:db<>fiddle
SELECT
least(
ceil(date_part('day', now()) / 5) * 5,
date_part('day', date_trunc('month', now()) + interval '1 month - 1 day')
)
I have a function in postgresql which returns query based on the input supplied:
create or replace function func(last_month date, arg1 varchar default 'any')
returns table(id bigint, start_date date, end_date date) as $$
begin
if arg1 = 'multiple' then
SELECT DISTINCT id, (last_month - interval '1 year' + interval '1 month')::date as start_date,
last_month as end_date
FROM table
WHERE month BETWEEN (last_month - interval '1 year' + interval '1 month')::date
AND last_month
and month >= '2017-09-01'
AND activity >= 5;
else
SELECT DISTINCT id, (last_month - interval '1 year' + interval '1 month')::date as start_date,
last_month as end_date
FROM table
WHERE month BETWEEN (last_month - interval '1 year' + interval '1 month')::date
AND last_month
and month >= '2017-09-01'
end if;
end; $$ language sql;
However when I run it, it gives me the following error :
syntax error at or near "if"
I have checked returning only integer for testing purposes and it works and syntax appears to be fine. How can I return different query results from a function based on the given input.
I was able to resolve in he following way:
create or replace function func(last_month date, arg1 varchar default 'any')
returns table(id bigint, start_date date, end_date date) as $BODY$
begin
case arg1
when arg1 = 'multiple' then
return query
SELECT DISTINCT id, (last_month - interval '1 year' + interval '1 month')::date as start_date,
last_month as end_date
FROM table
WHERE month BETWEEN (last_month - interval '1 year' + interval '1 month')::date
AND last_month
and month >= '2017-09-01'
AND activity >= 5;
else
return query
SELECT DISTINCT id, (last_month - interval '1 year' + interval '1 month')::date as start_date,
last_month as end_date
FROM table
WHERE month BETWEEN (last_month - interval '1 year' + interval '1 month')::date
AND last_month
and month >= '2017-09-01';
end case;
end;
$BODY$ language plpgsql;
I have two tables that have date fields in them. I want to select data from table 1 where the date is +/- 1 day from any date in table 2.
try something like this :
select * from table1,table2
where table1.date BETWEEN (table2.date - '1 day'::interval)
AND (table2.date + '1 day'::interval)
and ...
If only +/- 1 day, you could use a workaround like this:
select col1, col2, ...
from table1
where date_col in (select distinct date_col
from table2
union all
select distinct (date_col - '1 day'::interval)
from table2
union all
select distinct (date_col + '1 day'::interval)
from table2
);
This has quite good peformance because the subquery only be calculated one time and will be cache for comparing