What is the Impala SQL equivalent function of NEXTDAY in Netezza? - date

I have a SELECT statement that I am trying to convert from Netezza SQL to Impala SQL. The output looks something like 140612, which is a date that is obtained by subtracting 7 from the current date and then pulling out the monday of that week.
I need to have this readable for Impala, then format it, then turn it into a string.
The query is :
TO_CHAR(next_day(DATE(a.date)-7, 'Monday'), 'YYMMDD') AS START_DATE

Assuming a.date is a timestamp, and T is the day of the week (1 = Sunday, 7 = Saturday; for your example above, Monday = 2, so T = 2) you should be able to use use
date_add(a.date, 7 - pmod(dayofweek(a.date) - T, 7));
in place of next_day in the above query. Check out the documentation on Impala's built-in date and time functions for more detail.

Related

How do you find the first date of the week in SAS from a date?

I have a variable in a SAS dataset that has a number of dates (e.g. 01APR21). What I'm looking to do is create a new variable that shows the date of the first Monday of that week. So using the above example of 01APR21, the output would be 29/03/2021 as that what was when the Monday in that week was. I'm assuming it's using intnx, but I can't get my head around it.
data test;
format date date8.;
format first_day date10.;
date = '01APR21'd;
first_day = ?;
run;
INTNX Parameters:
Interval : WEEK
Increment: 0 (same week)
Alignment: Beginning
(Sunday)
Then add 1 to get to Monday instead of Sunday. You could probably play with the SHIFT INDEX parameter as well.
Monday = intnx('week', dateVariable, 0, 'B') + 1

Number of days in a month in DB2

Is there a way to find the number of days in a month in DB2. For example I have a datetime field which I display as Jan-2020, Feb-2020 and so on. Based on this field I need to fetch the number of days for that month. The output should be something like below table,
I'm using the below query
select reportdate, TO_CHAR(reportdate, 'Mon-YYYY') as textmonth from mytable
Expected output
ReportDate textMonth No of Days
1-1-2020 08:00 Jan-2020 31
1-2-2020 09:00 Feb-2020 29
12-03-2020 07:00 Mar-2020 31
Try this:
/*
WITH MYTABLE (reportdate) AS
(
VALUES
TIMESTAMP('2020-01-01 08:00:00')
, TIMESTAMP('2020-02-01 09:00:00')
, TIMESTAMP('2020-03-12 07:00:00')
)
*/
SELECT reportdate, textMonth, DAYS(D + 1 MONTH) - DAYS(D) AS NO_OF_DAYS
FROM
(
SELECT
reportdate, TO_CHAR(reportdate, 'Mon-YYYY') textMonth
, DATE(TO_DATE('01-' || TO_CHAR(reportdate, 'Mon-YYYY'), 'dd-Mon-yyyy')) D
FROM MYTABLE
);
Db2 has the function DAYS_TO_END_OF_MONTH and several others which you could use. Based on your month input, construct the first day of the month. This should be something like 2020-01-01 for Jan-2020 or 2020-02-01 for Feb-2020. Follow the link for several other conversion functions which allow you to transform between formats and to perform date arithmetics.
convert your column to a proper date and try this: day(last_day(date_column))

Convert year and month variables to timestamp in Postgresql

I have to variables: year and month, both of type integer.
E.g:
year = 2016
month = 1
I want to, in my select statement, return a timestamp given those two variables.
I've had a look at the documentation, specifically to_timestamp and to_date, but all the examples I've come across show a string being converted into a timestamp.
I do not really want to convert my year and month into a string, such as:
to_timestamp(to_char(int,year) + ' ' + to_char(int, month),YYYY/MM/DD HH24:MI:SS)
So, how can I (if it is possible) convert my year and month into a timestamp?
If you are using Postgres 9.4 or later, you could try using make_timestamp():
make_timestamp(2016, 1, 1, 0, 0, 0.0)
This would create a timestamp for January 1, 2016 at midnight. We need to specify values for the other components, even if they end up not being relevant to your query/calculation (e.g. you only need the date).

DateDiff not available on Access 2013

I am trying to use the so called DateDiff function to subtract the End Date from the Start Date and obtain the numbers of days apart.For example:
10/11/1995 - 7/11/1995 = 3 (extract the 'dd' from DD/MM/YYYY format)
As date values are double with the integer part counting for a day, you can use this simple expression:
[Due Date]-[Start Date]
or, for integer days only:
Fix([Due Date]-[Start Date])
That said, you should a query for tasks like this.

Problem when extracting year and week number from string in PSQL

Let's say that I have a range of SQL tables that are named name_YYYY_WW where YYYY = year and WW = week number. If I call upon a function that guides a user defined date to the right table.
If the date entered is "20110101":
SELECT EXTRACT (WEEK FROM DATE '20110101') returns 52 and
SELECT EXTRACT (YEAR FROM DATE '20110101') returns 2011.
While is nothing wrong with these results I want "20110101" to either point to table name_2010_52 or name_2011_01, not name_2011_52 as it does now when I concanate the results to form the query for the table.
Any elegant solutions to this problem?
The function to_char() will allow you to format a date or timestamp to output correct the iso week and iso year.
SELECT to_char('2011-01-01'::date, 'IYYY_IW') as iso_year_week;
will produce:
iso_year_week
---------------
2010_52
(1 row)
You could use a CASE:
WITH sub(field) AS (
SELECT CAST('20110101' AS date) -- just to test
)
SELECT
CASE
WHEN EXTRACT (WEEK FROM field ) > 1 AND EXTRACT (MONTH FROM field) = 1 AND EXTRACT (DAY FROM field) < 3 THEN 1
ELSE
EXTRACT (WEEK FROM field)
END
FROM
sub;