I need to substract 4 hours from CURRENT_TIMESTAMP in DB2, my query in SQL DEVELOPER is correct because I can see the registers I need to see, but when I do the query in Eclipse have some problem and I don't know which is. This is the query I need to do:
"SELECT yerror, COUNT(yerror) AS CantidadErrores FROM kexg.VD03154 WHERE tumod BETWEEN (CURRENT_TIMESTAMP - 4 HOUR) AND CURRENT_TIMESTAMP GROUP BY yerror;";
This query returns me an error but if I put 24 HOUR is correct. Also is correct if I put 5 DAYS for example.
I have try to subtract 04 HOUR, and it's wrong also.
Thanks in advance
The following works beautifully for me on DB2 for z/OS:
select current timestamp as rightnow,
current timestamp - 4 hours
from sysibm.sysdummy1
;
RIGHTNOW COL1
-------------------------- --------------------------
2020-02-27-08.16.55.142456 2020-02-27-04.16.55.142456
Related
Must be missing something very simple here. Maybe someone can answer this. You want to select from a datetimestamp to now. Why would the where clause return nothing with this?
select * from xyz where ('2020-01-29 04:18:00-06'::timestamptz > CURRENT_TIMESTAMP);
when
select CURRENT_TIMESTAMP;
current_timestamp
-------------------------------
2020-01-29 04:47:06.011133-06
(1 row)
Time: 0.258 ms
Should not be that hard in PostgreSQL to get every row from a certain time to current time to see what has been added or new / changed.
I found the answer to this problem with the help here. First try I did not post was using between. It should have been used like this. Need to remove timestamp from the where clause and use BETWEEN!
TABLENAME.COL-NAME-FOR-TIMESTAMP BETWEEN '2020-01-29 04:18:00-06' AND CURRENT_TIMESTAMP
TABLENAME.COL-NAME-FOR-TIMESTAMP should be your column in the table you are referencing for datetime.
Hope this helps someone!
The explanation is that your current timestamp, in the time zone of your Postgres server, is past 4:18am on January 29, 2020. Try setting your time zone to something which should make your current query pass, e.g.
SET timezone = 'America/Los_Angeles'; -- 2:58 AM as of the time this answer was posted
SELECT * FROM xyz WHERE '2020-01-29 04:18:00-06'::timestamptz > CURRENT_TIMESTAMP;
I suspect that the doubt here is that you are expecting your Postgres server to be set to a certain time zone, so you should look into this.
In PostgreSQL i want to create script which can delete old data of before 1 month from A table(which contain many rows) and insert this data into one new alias table. and i want to execute this script every month.
for that i have created script as
insert into B select * from A where date >(now-'30 day'::interval);
delete from A where date <(now()-'30 days.
but in some month there is 30 days and in some 31 days .so how can i set this in cron tab to delete exact data and move in alias table.
While Laurenz answer makes much sense and seems to be a good guess of what OP really wants (cron monthly probably means he wants to flush not "older than one month", but of "previous month" so date_trunc to month is a case)
Yet answering it the other way (as I understand the original post):
begin;
insert into B select * from A where date >(now()-'1 month'::interval);
delete from A where date <(now()-'1 month'::interval);
end;
will delete not all data for previous month, but same timestamp one month ago, eg:
t=# select now()-'1 month'::interval;
?column?
-------------------------------
2017-05-12 07:31:31.785402+00
(1 row)
And with this logic you might want to schedule this data purge daily, not monthly - to keep last month data in active table, not "up to two" untill cron fires...
run it on the first of every month and write it like this:
... WHERE date >= date_trunc('month', current_timestamp) - INTERVAL '1 month'
AND date < date_trunc('month', current_timestamp)
If your table contains a lot of data, you might want to look into partitioning.
When we use the query like this in oracle to get the the total number of hours in round figure,
hours= select round(out_time-in_time)*24 from table_name;
what is the datatype of hours here?
out_time and in_time are column names
You can take NUMBER as the datatype in your case.
EDIT:- This will return you an integer
select 24 * round((to_date('2013-07-07 22:00', 'YYYY-MM-DD hh24:mi')
- to_date('2013-07-07 19:30', 'YYYY-MM-DD hh24:mi'))) diff_hours
from table_name;
Maybe a datatype called "INTERVAL" will suit you. It's called:
INTERVAL DAY [(day_precision)] TO SECOND
Stores a period of time in days, hours, minutes, and seconds
Interval is something that can we added (or substrated) to a DATE or TIMESTAMP.
see: http://docs.oracle.com/cd/E11882_01/server.112/e26088/sql_elements001.htm
I have an application in which I've used MySQL. I had a report that stretched records of the last 24 hours. I used the query:
WHERE (DATE_SUB(CURDATE(), INTERVAL 1 DAY) <= FROM_UNIXTIME(`workorder`.`CREATEDTIME` / 1000))
Now I have to use PostgreSQL and do not know how to make a report of the last 24 hours.
Can any of you help?
WHERE workorder.createdtime > current_date - 1 -- Yesterday and today
WHERE workorder.createdtime > current_timestamp - interval '1 day' -- last 24hr
> TIMESTAMP 'yesterday'
For convenience, Postgres includes a few hard-coded values as special Date/Time inputs. They include:
yesterday
today
tomorrow
now
Try SELECT TIMESTAMP 'now'.
For example, here is a query.
SELECT when_row_created_
FROM customer_
WHERE when_row_created_ > TIMESTAMP 'yesterday'
ORDER BY when_row_created_ DESC
;
These commands may not be appropriate to production code, but they certainly are handy in development. Read the docs and do some practice to be sure you understand the behavior of these commands, how the session’s time zone affects them and so on.
Downsides include (a) implicitly ignoring the crucial issue of time zone, and (b) not standard SQL.
where workorder.createdtime >= now() - interval '24 hour'
WHERE workorder.createdtime::date = current_date - 1; --from yesterday
I'm a bit of newbie when it comes to postgres, so bear with me a wee bit and i'll see if i can put up enough information.
i insert weather data into a table every 10 mins, i have a time column that is stamped with an epoch date.
I Have a column of the last hrs rain fall, and every hr that number changes of course with the running total (for that hour).
What i would like to do is skim through the rows to the end of each hour, and get that row, but do it over the last 4 hours, so i would only be returning 4 rows say.
Is this possible in 1 query? Or should i do multiple queries?
I would like to do this in 1 query but not fussed...
Thanks
Thanks guys for your answers, i was/am a bit confused by yours gavin - sorry:) comes from not knowing this terribly well.
I'm still a bit unsure about this, so i'll try and explain it a bit better..
I have a c program that inserts data into the database every 10 mins, it reads the data fom a device that keeps the last hrs rain fall, so every 10 mins it could go up by x amount.
So i guess i have 6 rows / hr of data.
My plan was to go back (in my php page) every 7, which would be the last entry for every hour, and just grab that value. Hence why i would only ever need 4 rows.. just spaced out a bit!
My table (readings) has data like this
index | time (text) | last hrs rain fall (text)
1 | 1316069402 | 1.2
All ears to better ways of storing it too :) I very much appreciate your help too guys thanks.
You should be able to do it in one query...
Would something along the lines of:
SELECT various_columns,
the_hour,
SUM ( column_to_be_summed )
FROM ( SELECT various_columns,
column_to_be_summed,
extract ( hour FROM TIME ) AS the_hour
FROM readings
WHERE TIME > ( NOW() - INTERVAL '4 hour' ) ) a
GROUP BY various_columns,
the_hour ;
do what you need?
SELECT SUM(rainfall) FROM weatherdata WHERE time > (NOW() - INTERVAL '4 hour' );
I don't know column names but that should do it the ones in caps are pgsql types. Is that what you are after?
I am not sure if this is exactly what you are looking for but perhaps it may serve as a basis for adaptation.
I often have a requirment for producing summary data over time periods though I don't use epoch time so there may be better ways of manipulating the values than I have come up with.
create and populate test table
create table epoch_t(etime numeric);
insert into epoch_t
select extract(epoch from generate_series(now(),now() - interval '6 hours',interval '-10 minutes'));
To divide up time into period buckets:
select generate_series(to_char(now(),'yyyy-mm-dd hh24:00:00')::timestamptz,
to_char(now(),'yyyy-mm-dd hh24:00:00')::timestamptz - interval '4 hours',
interval '-1 hour');
Convert epoch time to postgres timestamp:
select timestamptz 'epoch' + etime * '1 second'::interval from epoch_t;
then truncate to hour :
select to_char(timestamptz 'epoch' + etime * '1 second'::interval,
'yyyy-mm-dd hh24:00:00')::timestamptz from epoch_t
To provide summary information by hour :
select to_char(timestamptz 'epoch' + etime * '1 second'::interval,
'yyyy-mm-dd hh24:00:00')::timestamptz,
count(*)
from epoch_t
group by 1
order by 1 desc;
If you might have gaps in the data but need to report zero results use a generate_series to create period buckets and left join to data table.
In this case I create sample hour buckets back prior to the data population above - 9 hours instead of 6 and join on the conversion of epoch time to timestamp truncated to hour.
select per.sample_hour,
sum(case etime is null when true then 0 else 1 end) as etcount
from (select generate_series(to_char(now(),
'yyyy-mm-dd hh24:00:00')::timestamptz,
to_char(now(),'yyyy-mm-dd hh24:00:00')::timestamptz - interval '9 hours',
interval '-1 hour') as sample_hour) as per
left join epoch_t on to_char(timestamptz 'epoch' + etime * '1 second'::interval,
'yyyy-mm-dd hh24:00:00')::timestamptz = per.sample_hour
group by per.sample_hour
order by per.sample_hour desc;