In PostgreSQL I want to concat the current_timestamp with an interval as follows:
select current_timestamp + interval 2||' days'
But when I do, I get an error:
[Err] ERROR: syntax error at or near "2"
LINE 1: select current_timestamp + interval 2||' days'
But if I do it like this, it works correctly:
select current_timestamp + interval '2 days'
Why does one work, but not the other?
With reference to the following page
http://www.postgresql.org/docs/8.0/static/functions-datetime.html
Part of the problem is that the standard SQL expression for intervals quotes the number, but not the keywords. So you have to be careful.
select current_date, current_date + interval '2' day;
--
2012-02-21 2012-02-23 00:00:00
In PostgreSQL, quoting like '2 day' and '2 days' also works. So you might think that '2' || ' days' would be equivalent, but it's not.
select current_date, current_date + interval '2' || ' days';
--
2012-02-21 2012-02-21 00:00:02 days
The solution, as A.H. said, is to cast the result string as an interval.
You can also use a variable in place of 2. This generates a calendar for 2012.
-- 0 to 365 is 366 days; 2012 is a leap year.
select ('2012-01-01'::date + (n || ' days')::interval)::date calendar_date
from generate_series(0, 365) n;
I use that final cast to date, because date + interval returns a timestamp.
Please try this syntax:
select current_timestamp + ( 2 || ' days')::interval;
or even this one:
select current_timestamp + 2 * interval '1 day';
I use this
SELECT now() + (Var1 || ' ' || Var2)::interval
no concact function
Related
I would like to print this table (displaying only 4 rows for brevity):
Dates
Period
01-MAR-2022
61
02-MAR-2022
61
03-MAR-2022
61
30-APR-2022
61
So far I have:
SELECT CAST(TRUNC(date_trunc('month',CURRENT_DATE) + interval '-2 month') AS DATE) + (n || 'day')::INTERVAL AS Dates
, date_trunc('month',CURRENT_DATE) + interval '-2 month' + INTERVAL '2 month' - date_trunc('month',CURRENT_DATE) + interval '-2 month' AS Period
FROM generate_series(0,61) n
Please help with a better way of generating the period and also replacing the hard-coded 61 in generate_series(0,61).
Thanks!
What are you actually trying to accomplish, it is not clear nor specified. BTW your query is invalid. It appears you looking to list each data from first date of 2 months prior to the last date of 1 month prior and the total number of days in that range. The following would give the first date, and using date subtraction gives the number of days.
with full_range( first_dt, num_days) as
( select date_trunc ('month', (current_date - interval '2 months'))::date
, date_trunc ('month', (current_date - interval '1 day'))::date -
date_trunc ('month', (current_date - interval '2 months'))::date
)
select *
from full_range;
With that in hand you can use the num_days with generate series with the expression
select generate_series(0, num_days-1) from full_range
Finally combine the above arriving at: (see demo)
with full_range( first_dt, num_days) as
( select date_trunc ('month', (current_date - interval '2 months'))::date
, date_trunc ('month', (current_date - interval '1 day'))::date -
date_trunc ('month', (current_date - interval '2 months'))::date
)
select (first_dt + n*interval '1 day')::date, num_days
from full_range
cross join (select generate_series(0, num_days-1) from full_range) gn(n);
This is my current implementation
SELECT
date_trunc('month', do_date::date)::date as starting_of_the_month,
(date_trunc('month', do_date::date) + interval '1 month' - interval '1 day')::date as ending_of_the_month,
case when 1 + FLOOR((EXTRACT(DAY FROM do_date) - 1) / 7) = 1
THEN date_trunc('week', do_date)::date || ' - ' ||
(date_trunc('week', do_date) + '6 days') ::date end as week1,
case when 1 + FLOOR((EXTRACT(DAY FROM do_date) - 1) / 7) = 2
THEN date_trunc('week', do_date)::date || ' - ' ||
(date_trunc('week', do_date) + '6 days') ::date end as week2,
case when 1 + FLOOR((EXTRACT(DAY FROM do_date) - 1) / 7) = 3
THEN date_trunc('week', do_date)::date || ' - ' ||
(date_trunc('week', do_date) + '6 days') ::date end as week3,
case when 1 + FLOOR((EXTRACT(DAY FROM do_date) - 1) / 7) = 4
THEN date_trunc('week', do_date)::date || ' - ' ||
(date_trunc('week', do_date) + '6 days') ::date end as week4,
case when 1 + FLOOR((EXTRACT(DAY FROM do_date) - 1) / 7) = 5
THEN date_trunc('week', do_date)::date || ' - ' ||
(date_trunc('week', do_date) + '6 days') ::date end as week5
FROM sales_dos
WHERE date_trunc('month', do_date::date)::date >= '2021-02-01' AND date_trunc('month', do_date::date)::date < '2021-02-28'
This is my output for now :
I want the output to display as below :
Week 1 : 2021-02-01 - 2021-02-07
Week 2 : 2021-02-08 - 2021-02-14
Week 3 : 2021-02-15 - 2021-02-21
Week 4 : 2021-02-22 - 2021-02-28
Week 5 : -
Here is another way to do it (example for January 2021).
with
t as (select date_trunc('month', '2021-03-11'::date) as aday), -- any date in Jan-2021
s as
(
select d::date, d::date + 6 ed, extract('isodow' from d) wd
from t, generate_series (aday, aday + interval '1 month - 1 day', interval '1 day') d
)
select format ('Week %s', extract(day from d)::integer / 7 + 1) as weekname, d, ed
from s
where wd = 1;
So what you are looking for is a hybrid ISO with standard Calendar. You are taking the ISO week starting and ending period, but instead of all weeks being exactly 7 days you potentially truncate the 1st and/or last weeks.
The change to need for this is not actually extensive. For initial query returns the in the ISO week begin date instead of the 1st of the month. Then the main query then checks for week 1 and if so produces the 1st of the month. The only twist is determining the ISO week begin date. For this I've just included a function I have had for some time specifically for that. The change to the week_days function are marked --<<<.
create or replace function iso_first_of_week(date_in date)
returns date
language sql
immutable strict
/*
Given a date return the 1st day of the week according to ISO-8601.
I.e. Return the Date if it is Monday otherwise return the preceding Monday
*/
AS $$
with wk_adj(l_days) as (values (array[0,1,2,3,4,5,6]))
select date_in - l_days[ extract (isodow from date_in)::integer ]
from wk_adj;
$$;
create or replace
function week_dates( do_date_in date)
returns table (week_num integer, first_date date, last_date date)
language sql
immutable strict
as $$
with recursive date_list(week_num,first_date,terminate_date) as
( select 1
, iso_first_of_week(do_date_in)::timestamp --<<<
, (date_trunc('month', do_date_in) + interval '1 month' - interval '1 day')::timestamp
union all
select week_num+1, (first_date+interval '7 day'), terminate_date
from date_list
where first_date+interval '6 day' < terminate_date::timestamp
)
select week_num
, case when week_num = 1 --<<<
then date_trunc('month', do_date_in)::date --<<<
else first_date::date --<<<
end --<<<
, case when (first_date+interval '6 day')::date > terminate_date
then terminate_date::date
else (first_date+interval '6 day')::date
end last_date
from date_list;
$$;
---------- Original Reply
You can use a recursive query CTE to get the week number and first date for each week of the month specified. The main query calculates the ending date, shorting the last if necessary. Then wrap that into a SQL function to return the week number and date range for each week. See example.
create or replace
function week_dates( do_date_in date)
returns table (ween_num integer, first_date date, last_date date)
language sql
immutable strict
as $$
with recursive date_list(week_num,first_date,terminate_date) as
( select 1
, date_trunc('month', do_date_in)::timestamp
, (date_trunc('month', do_date_in) + interval '1 month' - interval '1 day')::timestamp
union all
select week_num+1, (first_date+interval '7 day'), terminate_date
from date_list
where first_date+interval '6 day' < terminate_date::timestamp
)
select week_num
, first_date::date
, case when (first_date+interval '6 day')::date > terminate_date
then terminate_date::date
else (first_date+interval '6 day')::date
end last_date
from date_list;
$$;
Response to: "How can i put the output in a single row with week1, week2, week3, week4 and week5". This is essentially the initial output that did not satisfy what you wanted. The term for this type action is PIVOT and is generally understood. It stems from transforming row orientation to column orientation. It is not overly difficult but it is messy.
IMHO this is something that belongs in the presentation layer and is not suitable for SQL. After all you are rearranging the data structure for presentation purposes. Let the database server use its natural format, use the presentation layer to reformat. This allows reuse of the queries instead of rewriting when the presentation is changed or another view of the same data is required.
If you actually want this then just use your initial query, or see the answer from
#Bohemian. However the below shows how this issue can be handled with just SQL (assuming the function week_dates was created).
select week1s
, case when week5e is null
then week4e
else week5e
end "end of month"
, week1s || ' - ' || week1e
, week2s || ' - ' || week2e
, week3s || ' - ' || week3e
, week4s || ' - ' || week4e
, week5s || ' - ' || week5e
from ( select max(case when (week_num=1) then first_date else NULL end) as week1s
, max(case when (week_num=1) then last_date else NULL end) as week1e
, max(case when (week_num=2) then first_date else NULL end) as week2s
, max(case when (week_num=2) then last_date else NULL end) as week2e
, max(case when (week_num=3) then first_date else NULL end) as week3s
, max(case when (week_num=3) then last_date else NULL end) as week3e
, max(case when (week_num=4) then first_date else NULL end) as week4s
, max(case when (week_num=4) then last_date else NULL end) as week4e
, max(case when (week_num=5) then first_date else NULL end) as week5s
, max(case when (week_num=5) then last_date else NULL end) as week5e
from week_dates(current_date)
) w ;
As before I have wrapped the above in a SQL function and provide an example here.
I would first simplify to:
extract(day from do_date)::int / 7 + 1 as week_in_month
then pivot on that using crosstab().
I am running simple query for DATE INTERVAL in my Redshift but it is giving an error for MONTH.
My query is as below:
select x,y, (x+y), DATE_ADD(NOW(), INTERVAL +1 MONTH) AS TIMEHERE from calc;
or
select x,y, (x+y), DATE_ADD(NOW(), INTERVAL 1 MONTH) AS TIMEHERE from calc;
it gives me an error like
Error: near line 6: near "MONTH": syntax error
I cannot figure out what the error is.
In redshift, you can add 1 month to the current date as follows:
dateadd(month, 1, getdate())
Or, if you don't want the time component:
dateadd(month, 1, current_date)
You can also do:
getdate() + interval '1 month'
Or:
current_date + interval '1 month'
As far as concerns there is no date_add() function in Redshift. In MySQL, however, you can do:
date_add(now(), interval 1 month)
Redshift -- like Postgres -- wants single quotes around the interval literal. So:
now() + interval '1 month'
Or because the time component is probably irrelevant:
current_date + interval '1 month'
I am trying to determine how to turn a day-of-year back into a date in PgSQL. When I do this
select date '2013-01-01' + interval '53 days'
I get a timestamp:
"2013-02-23 00:00:00"
So how come when I do any of the following
select extract(date from (date '2013-01-01' + interval '53 days'))
select extract(date from (select date '2013-01-01' + interval '53 days'))
I get "ERROR: timestamp units "date" not recognized"? Besides the why, how can I do what I want, which is to only get the date portion of the result of the original operation?
Use
select (date '2013-01-01' + interval '53 days')::date
or
select cast(date '2013-01-01' + interval '53 days' as date)
PostgreSQL's standard SQL function "extract()" will operate on timestamps, but a) "date" isn't a valid argument to extract(), and b) it returns subfields, not a collection of subfields. Conceptually, a date consists of a collection of three subfields: year, month, and day.
select extract(year from current_timestamp),
extract(month from current_timestamp),
extract(day from current_timestamp),
-- Concatenate and cast to type "date".
(extract(year from current_timestamp) || '-' ||
extract(month from current_timestamp) || '-' ||
extract(day from current_timestamp))::date
I have a server with PostgreSQL 8.4 which is being rebooted every night at 01:00 (don't ask) and need to get a list of connected users (i.e. their timestamps are u.login > u.logout):
SELECT u.login, u.id, u.first_name
FROM pref_users u
WHERE u.login > u.logout and
u.login > now() - interval '24 hour'
ORDER BY u.login;
login | id | first_name
----------------------------+----------------+-------------
2012-03-14 09:27:33.41645 | OK171511218029 | Alice
2012-03-14 09:51:46.387244 | OK448670789462 | Bob
2012-03-14 09:52:36.738625 | OK5088512947 | Sergej
But comparing u.login > now()-interval '24 hour' also delivers the users before the last 01:00, which is bad, esp. in the mornings.
Is there any efficient way to get the logins since the last 01:00 without doing string acrobatics with to_char()?
This should be 1) correct and 2) as fast as possible:
SELECT u.login, u.id, u.first_name
FROM pref_users u
WHERE u.login >= now()::date + interval '1h'
AND u.login > u.logout
ORDER BY u.login;
As there are no future timestamps in your table (I assume), you need no upper bound.
Some equivalent expressions:
SELECT localtimestamp::date + interval '1h'
, current_date + interval '1h'
, date_trunc('day', now()) + interval '1h'
, now()::date + interval '1h'
now()::date used to perform slightly faster than CURRENT_DATE in older versions, but that's not true any more in modern Postgres. But either is still faster than LOCALTIMESTAMP in Postgres 14 for some reason.
date_trunc('day', now()) + interval '1h' slightly differs in that it returns timestamptz. But it is coerced to timestamp according to the timezone setting of the current session in comparison to the timestamp column login, doing effectively the same.
See:
Ignoring time zones altogether in Rails and PostgreSQL
To return rows for the previous day instead of returning nothing when issued between 00:00 and 01:00 local time, use instead:
WHERE u.login >= (LOCALTIMESTAMP - interval '1h')::date + interval '1h'
select * from termin where DATE(dateTimeField) >= CURRENT_DATE AND DATE(dateTimeField) < CURRENT_DATE + INTERVAL '1 DAY'
This works for me - it selects ALL rows with todays Date.
select * from termin where DATE(dateTimeField) = '2015-11-17'
This works well for me!
An easy way of getting only time stamps for the current day since 01:00 is to filter with
CURRENT_DATE + interval '1 hour'
So your query should look like this:
SELECT u.login, u.id, u.first_name
FROM pref_users u
WHERE u.login > u.logout AND
u.login > CURRENT_DATE + interval '1 hour'
ORDER BY u.login;
Hope that helps.
where
u.login > u.logout
and
date_trunc('day', u.login) = date_trunc('day', now())
and
date_trunc('hour', u.login) >= 1
All answers so far are incorrect because they give the wrong answer between 0.00 and 1.00. So if you happen to run the query in that time period you get no results. Based on #ErwinBrandstetter's answer, what you want is this:
WHERE u.login > u.logout
AND u.login >= CASE WHEN NOW()::time < '1:00'::time THEN NOW()::date - INTERVAL '23 HOUR' ELSE NOW()::date + INTERVAL '1 HOUR' END;
I would love to do without the conditional but found no way to.
Edit: #ErwinBrandstetter did do it without a conditional, leaving this here for completeness.