Get all date from month - Oracle SQL - sql

I have two parameters MONTH and YEAR, how get all date?
Eg. YEAR = 2021, MONTH = 8
Date
------
01.08.2021
02.08.2021
.....
31.08.2021

I'm a fan of recursive CTEs, because they are standard SQL. In Oracle, you can use one like this:
with cte(dte) as (
select to_date('2020' || '8', 'YYYYMM') -- the two parameters are '2020' and '8'
from dual
union all
select dte + interval '1' day
from cte
where dte < last_day(dte)
)
select *
from cte;
Here is a db<>fiddle.

select dt + level - 1 as date_
from (select to_date(to_char(:year , 'fm0000') ||
to_char(:month, 'fm00'), 'yyyymm') as dt from dual)
connect by level <= add_months(dt, 1) - dt
;
This is almost the same as MT0's answer, with a few minor differences and one that is not entirely minor.
The to_date function assumes a default of first day of the month, so it is not necessary to explicitly concatenate '01' to the year and month (although perhaps doing so makes the code easier to read for beginner programmers). In my opinion, that's just a matter of taste.
I separated the computation of the first day of the month into a subquery. No worries, the optimizer will merge it into the outer query, so there is no efficiency cost - but the code will be easier to maintain.
The non-trivial difference is in the connect by clause. Even though mathematically the formula is equivalent to
dt + level - 1 < add_months(dt, 1)
or, better (still equivalent!)
dt + level <= add_months(dt, 1)
in terms of processing they are not equivalent. If written in the form above (previous line of code), for each value of level, the runtime will perform a date arithmetic calculation followed by a date comparison.
On the other hand, by solving the inequality for level (as I did in my query), the date calculation is performed just once (rather than once for every row), and the comparison is simply level <= some calculated number.
Perhaps in this problem "efficiency" plays no role, but as a matter of good coding, we should "solve for level" whenever possible, for the reason I just gave.

Assuming you pass in the bind variables :year and :month, then you can use a hierarchical query:
SELECT TO_DATE(
TO_CHAR(:year, 'FM0000') || TO_CHAR(:month, 'FM00') || '01',
'YYYYMMDD'
) + LEVEL - 1 AS "Date"
FROM DUAL
CONNECT BY
TO_DATE(
TO_CHAR(:year, 'FM0000') || TO_CHAR(:month, 'FM00') || '01',
'YYYYMMDD'
) + LEVEL - 1
<
ADD_MONTHS(
TO_DATE(
TO_CHAR(:year, 'FM0000') || TO_CHAR(:month, 'FM00') || '01',
'YYYYMMDD'
),
1
)
sqlfiddle here

Related

Compare dates from two queries PL/SQL

I have two queries , the first gets some data back from my table, the second query displays all half hour times between two specified dates. Is there a way of comparing the date results from query 1 from query 2 and merge the two results together when the date from query 2 doesn't exist in query 1 result.
I'll attach a little diagram to show what I mean.
Query 1:
SELECT
reading_date,
reading_value
FROM DCM_READING
WHERE reading_date BETWEEN TO_DATE('17-NOV-2019' || ' 000000', 'DD-MON-YYYY HH24MISS')
AND TO_DATE('19-NOV-2019' || ' 235959', 'DD-MON-YYYY HH24MISS')
ORDER BY reading_date;
Query 2:
select TO_DATE('17-NOV-2019' || ' 000000', 'DD-MON-YYYY HH24MISS') +
( level / 48 ) dt
from dual
connect by level <= ( 48 + ( 48 *
( TO_DATE('19-NOV-2019' || ' 000000', 'DD-MON-YYYY HH24MISS') -
TO_DATE('17-NOV-2019' || ' 000000', 'DD-MON-YYYY HH24MISS') )
)
) ;
You can enumerate the timestamps you want in a CTE, then bring the table with a left join:
with cte (reading_date) as (
select date '2020-11-17' from dual
union all
select reading_date + interval '30' minute
from cte
where reading_date + interval '30' minute < date '2020-11-19'
)
select c.reading_date, d.reading_value
from cte c
left join dcm_reading d on d.reading_date = c.reading_date
order by c.reading_date
I like to use recursive queries rather than Oracle specific connect by syntax, because they are standard SQL - but that's mostly a matter of taste, the logic remains the same.

Input value not long enough for date format

I am trying to show week numbers on a query. I have the following sql:
SELECT DISTINCT TO_CHAR(TRUNC((sysdate + ROWNUM), 'IW'), 'IW' ) as dt
FROM DUAL
CONNECT BY ROWNUM <= (2-1)*7
when I try to execute it it gives me the following error: input value not long enough for date format I know this is a common error but I can't find an solution to my answer.
It returns the following when I do it witouth to_char: 20/02/2017 00:00:00
Apparently this works:
SELECT DISTINCT TO_CHAR(TRUNC((SYSDATE) + (ROWNUM), 'IW'), 'IW') as dt
FROM DUAL
CONNECT BY ROWNUM <= (3-1)*7
don't really know what changed but it works now.

SQL Oracle How to convert String Week into date

I have dates stored like String in database.
The format is 'yyyy-ww' (example: '2015-43').
I need to get the first day of the week.
I tried to convert this string into date but there is no 'ww' option for the function "to_date".
Do you have an idea to perform this convertion?
EDIT
Test results based on the answers -
Thanks for your anwsers, but I have many problems to apply your solutions to my context:
select
TRUNC ( 2015 + ((43 - 1) * 7), 'IW' )
from dual
==> Error : ORA-01722: invalid number
select
TRUNC(to_date('2015','YYYY')+ to_number('01') *7, 'IW')
from dual
==> 2015-02-02 00:00:00
I waited for a date in january
select
trunc(to_date(regexp_substr('2015-01', '\d+',1,2), 'YYYY') + regexp_substr('2015-01', '\d+') * 7, 'IW') dt2
from dual
==> 0039-09-14 00:00:00
select
regexp_substr('2015-01', '\d+',1,2) as res1,
regexp_substr('2015-01', '\d+') * 7 as res2
from dual
==> res1 = 01
==> res2 = 14105
try to use by truncate
with t as (
select '16-2010' dt from dual
)
--
--
select dt,
trunc(to_date(regexp_substr(dt, '\d+',1,2), 'YYYY') + regexp_substr(dt, '\d+') * 7, 'IW') dt2
from t
I have dates stored like String in database.
You should never do that. It is a bad design. you should store date as DATE and not as a string. For all kinds of requirements for date manipulations Oracle provides the required DATE functions and format models. As and when needed, you could extract/display the way you want.
I need to get the first day of the week.
TRUNC (dt, 'IW') returns the Monday on or before the given date.
Anyway, in your case, you have the literal as YYYY-WW format. You could first extract the year and week number and combine them together to get the date using TRUNC.
TRUNC ( year + ((week_number - 1) * 7)
, 'IW
)
So, the above should give you the Monday of the week number passed for that year.
SQL> WITH DATA AS
2 ( SELECT '2015-43' str FROM dual
3 )
4 SELECT TRUNC(to_date(SUBSTR(str, 1, 4),'YYYY')+ to_number(SUBSTR(str, instr(str, '-',1)+1))*7, 'IW')
5 FROM DATA
6 /
TRUNC(TO_
---------
23-NOV-15
SQL>
Similar to Lalit's, however, I think I've corrected the math (his seemed to be off a bit when I tested .. )
with w_data as (
select sysdate + level +200 d from dual connect by level <= 10
),
w_weeks as (
select d, to_char(d,'yyyy-iw') c
from w_data
)
SELECT d, c, trunc(d,'iw'),
TRUNC(
to_date(SUBSTR(c, 1, 4)||'0101','yyyymmdd')-8+to_char(to_date(SUBSTR(c, 1, 4)||'0101','yyyymmdd'),'d')
+to_number(SUBSTR(c, instr(c, '-',1)+1)-1)*7 ,'IW')
FROM w_weeks;
The extra columns help show the dates before, and after.
I would do the following:
WITH d1 AS (
SELECT '2015-43' AS mydate FROM dual
)
SELECT TRUNC(TRUNC(TO_DATE(REGEXP_SUBSTR(mydate, '^\d{4}'), 'YYYY'), 'YEAR') + (COALESCE(TO_NUMBER(REGEXP_SUBSTR(mydate, '\d+$')), 0)-1) * 7, 'IW')
FROM d1
The first thing the above query does is get the first four digits of the string 2015-43 and truncates that to the closest year (if you convert convert 2015 using TO_DATE() it returns a date within the current month; that is SELECT TO_DATE('2015', 'YYYY') FROM dual returns 01-FEB-2015; we need to truncate this value to the YEAR in order to get 01-JAN-2015). I then add the number of weeks minus one times seven and truncate the whole thing by IW. This returns a date of 01-OCT-2015 (see SQL Fiddle here).
According ISO the 4th of January is always in week 1, so your query should look like
Select
TRUNC(TO_DATE(REGEXP_SUBSTR(your_column, '^\d{4}')||'-01-04', 'YYYY-MM-DD')
+ 7*(REGEXP_SUBSTR(your_column, '\d$')-1), 'IW')
from your_table;
However, there is a problem. ISO year used for Week number can be different than actual year. For example, 1st Jan 2008 was in ISO week number 53 of 2007.
I think a proper working solution you get only when you generate ISO weeks from date value.
WITH w AS
(SELECT TO_CHAR(DATE '2010-01-04' + LEVEL * INTERVAL '7' DAY, 'IYYY-IW') AS week_number,
TRUNC(DATE '2010-01-04' + LEVEL * INTERVAL '7' DAY, 'IW') AS first_day
FROM dual
CONNECT BY DATE '2010-01-04' + LEVEL * INTERVAL '7' DAY < SYSDATE)
SELECT your_Column, first_day
FROM w your_table
JOIN w ON week_number = your_Column;
Your date range must bigger than 2010-01-04 and not bigger than current day.
This is what I used:
select
to_date(substr('2017/01',1,4)||'/'||to_char(to_number(substr('2017/01',6,2)*7)-5),'yyyy/ddd') from dual;

Oracle SQl Dev, how to calc num of weekdays between 2 dates

Does anyone know how can I calculate the number of weekdays between two date fields? I'm using oracle sql developer. I need to find the average of weekdays between multiple start and end dates. So I need to get the count of days for each record so I can average them out. Is this something that can be done as one line in the SELECT part of my query?
This answer is similar to Nicholas's, which isn't a surprise because you need a subquery with a CONNECT BY to spin out a list of dates. The dates can then be counted while checking for the day of the week. The difference here is that it shows how to get the weekday count value on each line of the results:
SELECT
FromDate,
ThruDate,
(SELECT COUNT(*)
FROM DUAL
WHERE TO_CHAR(FromDate + LEVEL - 1, 'DY') NOT IN ('SAT', 'SUN')
CONNECT BY LEVEL <= ThruDate - FromDate + 1
) AS Weekday_Count
FROM myTable
The count is inclusive, meaning it includes FromDate and ThruDate. This query assumes that your dates don't have a time component; if they do you'll need to TRUNC the date columns in the subquery.
You could do it the following way :
Lets say we want to know how many weekdays between start_date='01.08.2013' and end_date='04.08.2013' In this example start_date and end_date are string literals. If your start_date and end_date are of date datatype, the TO_DATE() function won't be needed:
select count(*) as num_of_weekdays
from ( select level as dnum
from dual
connect by (to_date(end_date, 'dd.mm.yyyy') -
to_date(start_date, 'dd.mm.yyyy') + 1) - level >= 0) s
where to_char(sysdate + dnum, 'DY',
'NLS_DATE_LANGUAGE=AMERICAN') not in ('SUN', 'SAT')
Result:
num_of_weekdays
--------------
2
Checkout my complete working function code and explanation at
https://sqljana.wordpress.com/2017/03/16/oracle-calculating-business-days-between-two-dates-in-oracle/
Once you have created the function just use the function as part of the SELECT statement and pass in the two date columns for Start and End dates like this:
SELECT Begin_Date, End_Date, fn_GetBusinessDaysInterval(Begin_Date, End_Date) AS BusinessDays FROM YOURTABLE;

How can I extract and display the date range based on Quarter in Oracle?

I'm building a summary table as part of a stored procedure and I have two columns. The first column needs to show the start and the second column needs to show the end of a date range that is based from an input parameter that is a number designating the quarter. I was able to extract the following from AskTom but I have some questions.
Open C1 FOR
SELECT ( SELECT TRUNC (SYSDATE, 'Q')-1+1 AS 'StartOf' FROM DUAL ),
SELECT ( SELECT TRUNC(ADD_MONTHS (SYSDATE, +3), 'Q')-2 AS 'EndOf' FROM DUAL )
FROM DUAL;
Question 1. Will the Math here account for LeapYears... I don't think it will but I'm not sure how to handle that.
Question 2. How do I add the input parameter, 'inQuarter' as the specific quarter? I've tried putting it in place of sysdate but I need to reformat it into date first I think?
Thanks in advance for any responses.
Tom Kyte has givven you the answer:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:250288900346075009
Open C1 FOR
select add_months( dt, (inQuarter-1)*3 ),
last_day(add_months( dt, (inQuarter-1)*3+2 ) )
from (
select to_date( inYear || '0101', 'yyyymmdd' ) dt
from dual)
You can convert a numeric year and numeric quarter parameter to a DATE
SELECT add_months( trunc( to_date( to_char( <<numeric year>> ),
'YYYY' ),
'YYYY' ),
3 * <<numeric quarter>> ) first_of_quarter,
add_months( trunc( to_date( to_char( <<numeric year>> ),
'YYYY' ),
'YYYY' ),
4 * <<numeric quarter>> ) - 1 last_of_quarter,
FROM dual
The time component of both dates will be midnight on the last day of the quarter (i.e. 24 hours before the beginning of the next quarter). You may want the last of the quarter to be 23:59:59 on the last day of the quarter if you want the range to be inclusive of all possible dates in the quarter.
I suggest:
Open C1 FOR
SELECT TRUNC (d_inQuarter, 'Q') AS "StartOf",
TRUNC(ADD_MONTHS (d_inQuarter, +3), 'Q') AS "EndOf"
FROM (SELECT add_months(to_date(to_char(i_yr)||'-01-01','YYYY-MM-DD'), (i_q-1)*3)
AS d_inQuarter FROM DUAL);
- with integer parameters i_yr and i_q representing the year and quarter, respectively.
Note that EndOf will represent midnight on the first day of the next quarter, so any selection should be based on conditions < "EndOf", not <= "EndOf". (This should ensure that all times on the last day of the quarter are included.)