Retrieve previous month from date column that contains MONYYYY - sql

I need to change a date value that is coming from a table in the form of May2013 (MonYYYY). The column itself is a VARCHAR
In my select statement, I am looking to retrieve the previous month (Apr2013). I've done some research and found the following, if I were using SYSDATE:
select to_date(add_months(sysdate, 'MONYYY')-1) from dual
How do I make it work for the date structure I have above? I've tried:
select to_date(add_months(date.datetable, MONYYY)-1) from datetable

ADD_MONTHS function needs a date variable as input. So, first you need to convert your varchar column to date type and then apply the add_months function.
SELECT ADD_MONTHS (TO_DATE ('May2013', 'monyyyy'), -1) FROM DUAL;
The return type will be date. In this case, it returns 0th hour of first day of April.

Related

Query that will select a timeframe from specific date to today

I'm having issues in my WHERE clause selecting data from a specific day to today's date. The day/time format in my date column is '7/2/2020 3:12:08 PM'.
I've tested a couple options but keep getting this error - 'literal does not match format string'.
Any idea's of how I can select all data from March 1, 2020 to current date?
Thanks!
In Oracle date columns are not strings, they are exactly in date datatype, so you don't need to convert/cast it. Just use simple date literals:
https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/Literals.html#GUID-8F4B3F82-8821-4071-84D6-FBBA21C05AC1
select * from table where your_date_columg >= date'2015-12-31'
or with to_date function for your string:
select * from table
where
your_date_columg >= to_date('2019-11-25 13:57:52',
'yyyy-mm-dd hh24:mi:ss')

How to fetch month from date where date column is in varchar datatype. FYI using snowflake tool

How to fetch month from date where date column is in varchar datatype. FYI using snowflake tool.
For example if i want data of june month ? how can i fetch ?
You can use the TO_DATE(…) function to treat the VARCHAR column as a formatted date type, and the EXTRACT(…) function to retrieve just the month out of the date.
If your date string is formatted in a well-known manner, TO_DATE's automatic parsing (or a direct cast using the :: operator) will suffice, and you can write your query this way:
SELECT * FROM table
WHERE
EXTRACT(month, TO_DATE(varcharCol)) = 6 -- June of every year
AND EXTRACT(year, varcharCol::DATE) = 2020; -- June of 2020 alone
Alternatively, if the date is in a non-standard format, use available formatting options to make TO_DATE(…) parse it properly:
-- Dates of custom format, such as: 'June # 02 # 2020'
SELECT
EXTRACT(month, TO_DATE(varcharCol, 'MMMM # DD # YYYY')) AS month
FROM table
WHERE
month = 6;
Note: You can also swap all DATE and TO_DATE above with TIMESTAMP and TO_TIMESTAMP if the data carries a whole timestamp value within it instead of only a date.
First of all, you shouldn't store dates as strings. But you probably know that.
If you do store dates as strings, you store them all in one particular format, say, 'mm/dd/yyyy'. So, use a substring function to get the month digits.
For 'mm/dd/yyyy':
where substring(date_string, 1, 2) = '06'
For 'yyyy-mm-dd':
where substring(date_string, 9, 2) = '06'
In many situations you can also use LIKE:
For 'mm/dd/yyyy':
where date_string like '06%'
For 'yyyy-mm-dd':
where date_string like '%-06-%'
You have to use to_date in snowflake to convert varchar datatype to date as following
select *
from yourTable
where to_date(yourDateColumn, 'YYYY-MM-DD') >= '2020-06-01'
and to_date(yourDateColumn, 'YYYY-MM-DD') <= '2020-06-30'

Oracle - Convert datetime format

I have a temp table.
It has last_update column in 2/10/2018 6:01:50 PM datetime format.
How can I write THE BEST QUERY to display all information that's updated on 02-Oct-2018 day?
You can use trunc function
select *
from tab
where trunc(last_update) = date'2018-10-02'
It is preferable to avoid TRUNC especially if you have an index on the column last_update.
A simple where condition should be better and may be better performant.
WHERE last_update >= date '2018-10-02' AND
last_update < date '2018-10-02' + 1
Use trunc function for getting the same day:
trunc(last_update) = trunc(to_date('02-Oct-2018', 'DD-MONTH-YYYY'))
The TRUNC (date) function returns date with the time portion of the day truncated to the unit specified by the format model fmt. The value returned is always of datatype DATE, even if you specify a different datetime datatype for date. If you omit fmt, then date is truncated to the nearest day.
You can also use format DD-MON-YYYY

Next Occurance of day of next week (Specifically, the next occurance of Wednesday) based on the current date

In Oracle SQL Developer, how does one determine the calendar date of the next occurrence of Wednesday, based on the current date. I have searched and seen many examples for Ruby, PHP, MYSQL, but not for oracle sql. I read this article about DATETIME calculations, but these we have not gone over in class. We are working with date conversion, case, when, timestamps, and intervals but I'm not sure how to go about this problem.
Nex_day function will return the date of the first weekday, specified as the second parameter of the function, later than a date specified as the first parameter of the function. For example:
SQL> select next_day(sysdate, 'WEDNESDAY') next_day
2 from dual
3 ;
NEXT_DAY
-----------
05-DEC-2012
You can use DATE function called NEXT_DAY
Try this
SELECT NEXT_DAY(SYSDATE,'WEDNESDAY') "Next WED"
FROM DUAL ;

Oracle to_date function with quarter-format

I need to find some records created in a range of quarters. For example, I'm looking for all records created between the 4th quarter of 2008 and the 1st quarter of 2010. I have this in my WHERE-clause:
...and r.record_create_date between to_date('2008 4','YYYY Q')
and to_date('2010 1','YYYY Q')
but Oracle says: ORA-01820: format code cannot appear in date input format. The Q is a valid date format symbol, so I'm not sure what's happened. Is this even a valid way to find values in between calender quarters, or is there a better way?
Also interesting, and possibly related, if I execute this:
select to_date('2009','YYYY') from dual;
The value displayed in my IDE is 2009-08-01. I would have expected 2009-08-04, since today is 2010-08-04.
This:
select to_date('2009 1','YYYY Q') from dual;
of course, fails.
(Oracle 10g)
Oracle says: ORA-01820: format code cannot appear in date input format. The Q is a valid date format symbol, so I'm not sure what's happened.
See the second column of table 2.15 at http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements004.htm#i34948. Not all format elements are allowed when converting to dates, timestamps, etc.
I recommend against using between for date range checks. People often will miss values within the ending day that the expect to be included. So I would translate:
and r.record_create_date between to_date('2008 4','YYYY Q')
and to_date('2010 1','YYYY Q')
To
and to_date('2008-10-01', 'YYYY-MM-DD') <= r.record_create_date
and record_create_date < to_date('2010-04-01', 'YYYY-MM-DD') -- < beginning of 2Q2010.
Someone asked the same question on OTN: http://forums.oracle.com/forums/thread.jspa?threadID=1081398&tstart=255
The crux of the issue is that you can not specify "Q" in the TO_DATE function.
Given that you're already specifying a portion of the date, why not provide the entire date? Mind too that to_date('2010 1','YYYY Q') would give you Jan 1st, 2010 when you really want March 31st, 2010... at a second to midnight.
Since the relationship between quarters to months is one-to-many, it doesn't make sense to do TO_DATE('2008 1', 'yyyy q'); what date should be returned? The first of the quarter, the end of the quarter, ...? (On the other hand, converting a date to a quarter - like TO_CHAR(SYSDATE, 'yyyy q') makes sense because a specific date only exists in one quarter.)
So, if you do want a query that looks for a date that falls between two quarters, you will have to "rolll your own" (explicitly stating the dates of the start/end of a quarter.)
As a side note, in case anyone is considering not using TO_DATE please do not use things like: WHERE date_value BETWEEN 'date string1' and 'date string2' without the TO_DATE function. It assumes a default date format and under certain situations can avoid potentially useful indexes altogether.
Below is one example where the same query can have a different result.
select sysdate from dual where sysdate between '1-Jan-10' and '31-Dec-10';
SYSDATE
---------
04-AUG-10
SQL> alter session set nls_date_format = 'YYYY-MM-DD';
Session altered.
SQL> select * from dual where sysdate between '1-Jan-10' and '31-Dec-10';
no rows selected
(Notice that in the second instance no error is returned. It just assumes Jan 10, 0001 and Dec. 10th, 0031.)
I think the best way is to just input the quarter start date and quarter end dates without even bothering with to_date. I think if you use
between '1-Jan-10' and '31-Dec-10'
for example, then you don't (in Oracle I believe) need to_date and it isn't much more difficult than typing in the quarter number
To calculate in Oracle the first day of a quarter and the last day of a quarter from the year and quarter:
I Use the fact
start_month= -2 + 3 * quarter
last_month = 3 * quarter
variable v_year number
variable v_quarter number
exec :v_year :=2017
exec :v_quarter:=4
select :v_year as year,
:v_quarter as quarter,
to_date(:v_year||to_char(-2+3*:v_quarter,'fm00'),'yyyymm') as quarter_start,
last_day(to_date(:v_year||to_char(3*:v_quarter,'fm00')||'01 23:59:59','yyyymmdd hh24:mi:ss')) as quarter_end
from dual a;
YEAR|QUARTER|QUARTER_START |QUARTER_END
2017| 4|2017-10-01 00:00:00|2017-12-31 23:59:59