In MySQL I can use:
select *
from mytable
where created_at < DATE_SUB(NOW(), INTERVAL 1 MINUTE)
for filtering less than 10 minutes.
How to do that in PostgreSQL? The created at in style "2018-09-27 12:11:32".
select *
from mytable
where created_at < now()::timestamp - INTERVAL '10 min'
Related
I want to query data for last 30 days including today from redshift table. below is my query.
my date_column's type is 'timestamp without timezone'
select *
from mytable
WHERE date_column BETWEEN current_date - INTERVAL '30 day' AND current_date
order by date_column desc;
It gives the result for 30 days. But it doesn't include today's result.
I want to query for 30 days result including today's result also.
If it's a timestamp don't use between as it also compares the time part. Use a range query:
where date_column >= current_date - interval '30 day'
and date_column < current_date + interval '1 day'
Note that the upper bound is using < together with "tomorrow"
With Postgres this could be simplified to
where date_column >= current_date - 30
and date_column < current_date + 1
but Redshift isn't Postgres and I don't know if that would work there.
I have two tables, today's_table and yeterday's_table.
I need to compare the data for an interval of 15 mins at exact same times for today and yesterday.
For example, for below data let's I need to check from 00:00:00 and 00:15:00 on 20201202 and 20201202. So difference should come out as '3' since the yesterday's_table has 8 records and today's_table has 5 records.
today's_table:
Yesterday's table:
I tried something like; (consider now() is 00:15:00)
select count(*) from yeterday's_table where time between now() - interval "24 hours" and now() - interval "23 hours 45 mins"
minus
select count(*) from today's_table where time = now() - interval "15 minutes";
is there any other way to do this?
You can easily do this with subqueries:
SELECT b.c - a.c
FROM (select count(*) as c from yeterdays_table where time between now() - interval '24 hours' and now() - interval '23 hours 45 mins') a,
(select count(*) as c from todays_table where time = now() - interval '15 minutes') b;
Bear in mind you need to single-quote your intervals, and your table names cannot have quotes in them.
I have a table, time_slots, which has a column start_time. My users table has a column, hours_before (int), which is the number of hours before the start_time to receive a notification.
I'm running a job every 5 minutes that checks the time slots that have a start_time which is now + hours_before. All my datetimes are store in UTC. I can't figure out the correct where clause to get the appropriate time slots.
Right now I'm passing in the current time in UTC as a string rather than doing something like current_timestamp at time zone 'UTC'.
(extract(epoch from starts_at) - extract(epoch from (date '2020-11-09 06:20:00' + (users.hours_before * INTERVAL '1 hour')))) = 0
Here is a test query to see what the values are inside of a select. In this example, (6 * INTERVAL '1 hour') would be where users.hours_before would be. I'm using a static 6 while tinkering.
select
(extract(epoch from "starts_at") - extract(epoch from date '2020-11-09 06:20:00')) / 3600 as hours,
(extract(epoch from "starts_at") - extract(epoch from (date '2020-11-09 06:20:00' + (6 * INTERVAL '1 hour')))) as other_interval,
*
from
"time_slots"
where
"starts_at" > '2020-11-09 06:20:00'
order by hours asc;
For example, the following query has the same hours and other_interval values as the above query, despite the date being 2020-11-09 10:00:00 instead of 2020-11-09 06:00:00. Shouldn't those columns be 4 hours different since they change by 4 hours?
select
(extract(epoch from "starts_at") - extract(epoch from date '2020-11-09 10:00:00')) / 3600 as hours,
(extract(epoch from "starts_at") - extract(epoch from (date '2020-11-09 10:00:00' + (6 * INTERVAL '1 hour')))) as other_interval,
*
from
"time_slots"
where
"starts_at" >= '2020-11-09 06:00:00'
order by hours asc;
I want to subtract minute from NOW() and the value of "how many minutes" I am reading from another table:
SELECT * FROM A, B
WHERE
A.entity_type_id = B.entity_type_id
AND A.status = 'PENDING'
AND A.request_time < (NOW() - INTERVAL B.retry_interval MINUTE)
AND A.retry_count >= B.retry_allowed_count
Here the problem is B.retry_interval is fetched from another table, while normally the queries like these are A.request_time < (NOW() - INTERVAL '10 MINUTE')
How do I achieve this?
Multiply the interval by interval '1 minute'
SELECT *
FROM A, B
WHERE
A.entity_type_id = B.entity_type_id
AND A.status = 'PENDING'
AND A.request_time < NOW() - B.retry_interval * INTERVAL '1 minute'
AND A.retry_count >= B.retry_allowed_count
I know its quite old enough, but here what i do. Btw my postgres version is 9.4.18.
try using interval data type. Convert the number from column to sting and concat it.
SELECT *
FROM A, B WHERE
A.entity_type_id = B.entity_type_id
AND A.status = 'PENDING'
AND A.request_time < (NOW() - concat(B.retry_interval::text,'minute')::interval
AND A.retry_count >= B.retry_allowed_count
Thanks to my coworker who find "interval" data type
I have a table like this:
+------------+------------------+
|temperature |Date_time_of_data |
+------------+------------------+
| 4.5 |9/15/2007 12:12:12|
| 4.56 |9/15/2007 12:14:16|
| 4.44 |9/15/2007 12:16:02|
| 4.62 |9/15/2007 12:18:23|
| 4.89 |9/15/2007 12:21:01|
+------------+------------------+
The data-set contains more than 1000 records and I want to check for the minimum variability.
For every 30 minutes if the variance of temperature doesn't exceed 0.2, I want all the temperature values of that half an hour replaced by NULL.
Here is a SELECT to get the start of a period for every record:
SELECT temperature,
Date_time_of_data,
date_trunc('hour', Date_time_of_data)+
CASE WHEN date_part('minute', Date_time_of_data) >= 30
THEN interval '30 minutes'
ELSE interval '0 minutes'
END as start_of_period
FROM your_table
It truncates the date to hours (9/15/2007 12:12:12 to 9/15/2007 12:12:00)
and then adds 30 minutes if the date initially had more than 30 minutes.
Next - use start_of_period to group results and get min and max for every group:
SELECT temperature,
Date_time_of_data,
max(Date_time_of_data) OVER (PARTITION BY start_of_period) as max_temp,
min(Date_time_of_data) OVER (PARTITION BY start_of_period) as min_temp
FROM (previou_select_here)
Next - filter out the records, where the variance is more than 0.2
SELECT temperature,
Date_time_of_data
FROM (previou_select_here)
WHERE (max_temp - min_temp) <=0.2
And finally update your table
UPDATE your_table
SET temperature = NULL
WHERE Date_time_of_data IN (previous_select_here)
You may need to correct some spelling mistakes in this queries, before they work. I havent tested them.
And you can simplify them, if you need to.
P.S. If you need to filter out the data with variance less than 0.2 , you can simply create a VIEW from the third SELECT with
WHERE (max_temp - min_temp) > 0.2
And use the VIEW instead of table.
This query should do the job:
with intervals as (
select
date_trunc('hour', Date_time_of_data) + interval '30 min' * round(date_part('minute', Date_time_of_data) / 30.0) as valid_interval
from T
group by 1
having var_samp(temperature) > 0.2
)
select * from T
where
date_trunc('hour', Date_time_of_data) + interval '30 min' * round(date_part('minute', Date_time_of_data) / 30.0) in (select valid_interval from intervals)
The inner query (labeled as intervals) returns times when variance is over 0.2 (having var_samp(temperature) > 0.2). date_trunc ... expression rounds Date_time_of_data to half hour intervals.
The query returns nothing on the provided dataset.
create table T (temperature float8, Date_time_of_data timestamp without time zone);
insert into T values
(4.5, '2007-9-15 12:12:12'),
(4.56, '2007-9-15 12:14:16'),
(4.44, '2007-9-15 12:16:02'),
(4.62, '2007-9-15 12:18:23'),
(4.89, '2007-9-15 12:21:01')
;