I am trying to grab the following date ranges:
Current date - prior 6 weeks
51 weeks ago - 55 weeks ago
I have the following query, but it doesn't seem to work:
OR date(date) >= date(dateadd(week,-6, current_date))
OR date(date) >= date(dateadd(week,-55, current_date))
OR date(date) <= date(dateadd(week,-51, current_date))
Any ideas?
You should use AND for specifying the date range. Try the following where condition.
date(date) >= date(dateadd(week,-6, current_date))
OR (
date(date) >= date(dateadd(week,-55, current_date))
AND
date(date) <= date(dateadd(week,-51, current_date))
)
You would need to use date arithmetics:
select *
from the_table
where the_date_column <= current_date - interval '6 week'
or the_date_column between
current_date - interval '55 week'
and current_date - interval '51 week';
If the_date_column is actually a timestamp column (not a date column) you might want to cast it to a date to get rid of the time part using the_date_column::date
The manual explains all available date/time functions:
http://www.postgresql.org/docs/current/static/functions-datetime.html
Related
I essentially want to run a query like:
SELECT * FROM t where date={time right now to the minute}
Use date_trunc() for your exact question:
where date = date_trunc('minute', now())
However, I suspect you really want the span of one minute:
where date >= date_trunc('minute', now()) and
date < date_trunc('minute', now()) + interval '1 minute'
it sounds simple and it should be simple but for some reason I can't seem to make it happen in Netezza... So far I tried:
select *
from table
where placed_dt >= DATEADD(YEAR, DATEDIFF(YEAR, 0, GETDATE()) - 1, 0);
and it looked like dateadd function doesn't work on Netezza. So I tried:
select *
from table
where placed_dt between (current_date - interval 1 year) and current_date
but still had no luck. Any help would be appreciated!
If you want the last year from the current date:
where placed_dt >= current_date - interval '1 year'
Note that the single quotes are needed.
and you can include the <= current_date if that is also needed.
If you want the last calendar year, there are various methods, but one is:
where date_trunc('year', placed_dt) = date_trunc('year', current_date) - interval '1 year'
You may try:
SELECT *
FROM yourTable
WHERE
placed_dt >= ADD_MONTHS(DATE_TRUNC('year', current_timestamp), -12) AND
placed_at < DATE_TRUNC('year', current_timestamp);
In the above inquality in the WHERE clause, for a current year of 2020, the lower bound represents 2019-01-01 and the upper bound represents 2020-01-01.
I know I can use dateadd to add an interval to a date, what about subtracting, would I just use a negative number? Here is an example:
select "date_table"."id_date" >= date_trunc('month', dateadd(month,-18, current_date))
from "date_table"
what about subtracting, would I just use a negative number?
Yes. This works:
dateadd(month, -18, current_date)
You can also use add-months():
add_months(current_date, -18)
Or interval litterals:
current_date - interval '18 months'
current_date - interval '1 year, 6 months'
How to query (SELECT) in Postgresql, so that the results of a column with different dates, are between Sunday and Saturday of the current week.
Query fake example:
SELECT * FROM table WHERE datecolumn BETWEEN CURRENT WEEK
In another query, I have the number of the week in the year. How to make a SELECT for these dates, applying in the WHERE clause the specific week number in the specific year.
Query fake example:
SELECT * FROM table WHERE datecolumn BETWEEN WEEK15 FROM year 2020
Perhaps you can use something like this:
SELECT *
FROM table
WHERE
EXTRACT(week FROM datecolumn) = EXTRACT(week FROM NOW())
AND
EXTRACT(isoyear FROM datecolumn) = EXTRACT(isoyear FROM NOW())
The week is ISO-8601 week number. By definition, ISO weeks start on Mondays and the first week of a year contains January 4 of that year. In other words, the first Thursday of a year is in week 1 of that year.
In the ISO week-numbering system, it is possible for early-January dates to be part of the 52nd or 53rd week of the previous year, and for late-December dates to be part of the first week of the next year.
For example, 2005-01-01 is part of the 53rd week of year 2004, and 2006-01-01 is part of the 52nd week of year 2005, while 2012-12-31 is part of the first week of 2013.
It's recommended to use the isoyear field together with week to get consistent results.
If you need custom (non-ISO) week numbering - you will have to craft your own calculation.
I would recommend the following pair of conditions:
where
date_column >= current_date - extract(dow from current_date) * interval '1 day'
and date_column < current_date - (extract(dow from current_date) - 8) * interval '1 day'
Postgres' date_trunc(week, ...) starts weeks on Monday, so we need something a little more complicated, using extract(dow from ...), which returns 0 on Sundays.
The advantage of this approach is that it is SARGeable, since no function is applied to the column being filtered. This means that this would happily take advantage of an index on the date column.
I would use date_trunc(), but like this. For the current week:
where datecolumn >= date_trunc('week', now()) and
datecolumn < date_trunc('week', now()) + interval '1 week'
For the nth week of the year, this is trickier. I think this does what you want:
where datecolumn >= (date_trunc('week', now()) -
(extract(week from now()) - 1) * interval '1 week' +
<n> * interval '1 week'
) and
datecolumn < (date_trunc('week', now()) -
(extract(week from now()) - 1) * interval '1 week' +
(<n> + 1) * interval '1 week'
)
Both of these are structured so the computations are NOT on the columns, so they are compatible with using indexes.
i do have a query which works fine but I was just wondering if there are other ways or alternate method to bettter this.
I have a table where i am fetching those records exceeding or do not fall between 1 year time interval however there is only the year and ISO week number column in the table (integer values).
basically the logic is to check ISO WEEK - YEAR falls between 'current_date - interval '1 year' AND current_date.
My query is as below :
select * from raj_weekly_records where
(date_dimension_week > extract(week from current_date) and date_dimension_year = extract(year from current_date) )
or (date_dimension_week < extract(week from current_date) and (extract(year from current_date)-date_dimension_year=1) )
or(extract(year from current_date)-date_dimension_year>1);
Here date_dimension_week and date_dimension_year are the only integer parameters by which I need to check is there any other alternate or better way?.This code is working fine no issues here.
Here is an idea. Convert the year/week to a numeric format: YYYYWW. That is, the year times 100 plus the week number. Then you can do the logic with a single comparison:
select *
from raj_weekly_records
where date_dimension_year * 100 + date_dimension_week
not between (extract(year from current_date) - 1) * 100 + extract(week from current_date) and
extract(year from current_date) * 100 + extract(week from current_date)
(There might be an off-by one error, depending on whether the weeks at the ends are included or excluded.)
select *
from raj_weekly_records
where
date_trunc('week',
'0001-01-01 BC'::date + date_dimension_year * interval '1 year'
)
+ (date_dimension_week + 1) * interval '1 week'
- interval '1 day'
not between
current_date - interval '1 year' and current_date