Here is what I did:
Select count(check_id)
From Checks
Where timestamp::date > '2012-07-31'
Group by 1
Is it right to do it like I did or is there a better way? Should/could I have used the DateDIFF function in my WHERE clause? Something like: DATEDIFF(day, timestamp, '2012/07/31') > 0
Also, I need to figure out how I'd calculate the total rate of acceptance for this
time period? Can anyone provide their expertise with this?
Is it right to do it like I did or is there a better way?
Using a cast like that is a perfectly valid way to convert a timestamp to a date (I don't understand the reference to the non-existing datediff though - why would adding anything to a timestamp change it)
However, the cast has one drawback: if there is an index on the column "timestamp" it won't be used.
But as you just want a range after a certain date, there is no reason to cast the column to begin with.
The following will achieve the same thing as your query, but can make use of an index on the column "timestamp" in case there is one and using it is considered beneficial by the optimizer.
Select count(distinct check_id)
From Checks
Where "timestamp" > date '2012-07-31' + 1
Note the + 1 which selects the day after, otherwise the query would include rows that are on that date but after midnight.
I removed the unnecessary group by from your query.
If you want to get a count per day, then you will need to include the day in the SELECT list. In that case casting is a good way to do it:
Select "timestamp"::date, count(distinct check_id)
From Checks
Where "timestamp" > date '2012-07-31' + 1
group by "timestamp"::date
Related
I'm try to count distinct value in some columns in a table.
i have a logic and i try to write in 2 way
But i get diffent results from this two query.
Can any one help to clarify me? I dont know what wrong is code or i think.
SQL
select count(distinct membership_id) from members_membership m
where date_part(year,m.membership_expires)>=2019
and date_part(month,m.membership_expires)>=7
and date_part(day,m.membership_expires)>=1
and date_part(year,m.membership_creationdate)<=2019
and date_part(month,m.membership_creationdate)<=7
and date_part(day,m.membership_creationdate)<=1
;
select count(distinct membership_id) from members_membership m
where m.membership_expires>='2019-07-01'
and m.membership_creationdate<='2019-07-01'
;
I actually think that this is the query you intend to run:
SELECT
COUNT(DISTINCT membership_id)
FROM members_membership m
WHERE
m.membership_expires >= '2019-07-01' AND
m.membership_creationdate < '2019-07-01';
It doesn't make sense for a membership to expire at the same moment it gets created, so if it expires on midnight of 1st-July 2019, then it should have been created strictly before that point in time.
That being said, the problem with the first query is that, e.g., the restriction on the month being on or before July would apply to every year, not just 2019. It is difficult to write a date inequality using the year, month, and day terms separately. For this reason, the second version you used is preferable. It is also sargable, meaning that an index on membership_expires or membership_creationdate can be used.
There is an issue with the first query:
select count(distinct membership_id) from members_membership m
where date_part(year,m.membership_expires)>=2019
and date_part(month,m.membership_expires)>=7
and date_part(day,m.membership_expires)>=1
and date_part(year,m.membership_creationdate)<=2019
and date_part(month,m.membership_creationdate)<=7
and date_part(day,m.membership_creationdate)<=1; -- do you think that any day is less than 1??
-- this condition will be satisfy by only 01-Jul-2019, But I think you need all the dates before 01-Jul-2019
and date_part(day,m.membership_creationdate)<=1 is culprit of the issue.
even membership_creationdate = 15-jan-1901 will not satisfy above condition.
You need to always use date functions on date columns to avoid such type of issue. (Your second query is perfectly fine)
Cheers!!
The reason could be due to a time component.
The proper comparison for the first query is:
select count(distinct membership_id)
from members_membership m
where m.membership_expires >= '2019-07-01' and
m.membership_creationdate < '2019-07-02'
--------------------------------^ not <= ---^ next day
This logic should work regardless of whether or not the "date" has a time component.
I want to write a query where in I need to specify the custom range (instead of hardcoded date range) for date starting from the order day. In the table being used, I have the date for the order.
As of now I have hardcoded the date range like:
where owh.order_day between TO_DATE('2016/07/15','YYYY/MM/DD') and TO_DATE('2017/01/17','YYYY/MM/DD')
where order_day is a date.
But rather I want something like:
where owh.order_day between TO_DATE(owh.order_day - 1,'YYYY/MM/DD') and TO_DATE(owh.order_day +3,'YYYY/MM/DD')
I am doing "-1" as it's "between", so it will take from order_day - order_day+2
For example, If the order_day is: "17/01/2016" then I want the condition to be where the date range is dynamically calculated as: "16/01/2016 - 20/01/2016" .
Is something like this possible? If yes, how can we achieve in in SQL??
The DB in question is Oracle
Any leads appreciated
Since you have not told us which RDBMS you are using, and since you are saying "any leads appreciated", I suppose we are free to give an answer for any RDBMS. The following will work for MySQL:
BETWEEN DATE_SUB( somedate, INTERVAL 1 DAY ) AND DATE_ADD( somedate, INTERVAL 1 DAY )
(source: https://www.tutorialspoint.com/sql/sql-date-functions.htm#function_date-add)
I would like to create a WHERE condition to return results where only 1 day has passed between two timestamps. I tried this:
SELECT * FROM RDMAVWSANDBOX.VwNIMEventFct
INNER JOIN VwNIMUserDim ON VwNIMUserDim.NIM_USER_ID = VwNIMEventFct.NIM_USER_ID
INNER JOIN rdmatblsandbox.TmpNIMSalesForceDB ON TmpNIMSalesForceDB.EMAIL = VwNIMUserDim.USER_EMAIL_ADDRESS
WHERE (CONTRACT_EFFECTIVE_DATE - EVENT_TIMESTAMP) =1
But the result was an error message "Invalid Operation On An ANSI DATETIME value".
I guess that, looking at the code now, Teradata has no way of knowing whether the "1" in "= 1" is a day, hour or year.
How would I select data where only 1 day has passed between CONTRACT_EFFECTIVE_DATE and EVENT_TIMESTAMP?
Same again for 2 days, and 3 days etc?
If both columns are DATEs you can use =1which means one day.
For Timestamps you need to tell what kind of interval you want:
WHERE (CONTRACT_EFFECTIVE_DATE - EVENT_TIMESTAMP) DAY = INTERVAL '1' DAY
But i'm not shure if this is what you really want, what's your definition of 1 day?
Edit:
Based on your comment the best way should be:
WHERE CAST(CONTRACT_EFFECTIVE_DATE AS DATE) - CAST(EVENT_TIMESTAMP AS DATE) = 1
This avoids dealing with INTERVAL arithmetic :-)
Not sure about Teradata, but I think most versions of SQL have built-in date math functions. In MSSQL for instance you could do this:
...
WHERE DATEDIFF(DAY, CONTRACT_EFFECTIVE_DATE, EVENT_TIMESTAMP) = 1
Or if you wanted to make sure 24 hours had passed you could do:
...
WHERE DATEDIFF(HOUR, CONTRACT_EFFECTIVE_DATE, EVENT_TIMESTAMP) = 1
Other SQL's have their own versions of this, and you may have to use 'D' or 'DD' instead of 'DAY' or something (and maybe 'HH' instead of 'HOUR' likewise).
I am trying to query my postgresql db to return results where a date is in certain month and year. In other words I would like all the values for a month-year.
The only way i've been able to do it so far is like this:
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN '2014-02-01' AND '2014-02-28'
Problem with this is that I have to calculate the first date and last date before querying the table. Is there a simpler way to do this?
Thanks
With dates (and times) many things become simpler if you use >= start AND < end.
For example:
SELECT
user_id
FROM
user_logs
WHERE
login_date >= '2014-02-01'
AND login_date < '2014-03-01'
In this case you still need to calculate the start date of the month you need, but that should be straight forward in any number of ways.
The end date is also simplified; just add exactly one month. No messing about with 28th, 30th, 31st, etc.
This structure also has the advantage of being able to maintain use of indexes.
Many people may suggest a form such as the following, but they do not use indexes:
WHERE
DATEPART('year', login_date) = 2014
AND DATEPART('month', login_date) = 2
This involves calculating the conditions for every single row in the table (a scan) and not using index to find the range of rows that will match (a range-seek).
From PostreSQL 9.2 Range Types are supported. So you can write this like:
SELECT user_id
FROM user_logs
WHERE '[2014-02-01, 2014-03-01]'::daterange #> login_date
this should be more efficient than the string comparison
Just in case somebody land here... since 8.1 you can simply use:
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN SYMMETRIC '2014-02-01' AND '2014-02-28'
From the docs:
BETWEEN SYMMETRIC is the same as BETWEEN except there is no
requirement that the argument to the left of AND be less than or equal
to the argument on the right. If it is not, those two arguments are
automatically swapped, so that a nonempty range is always implied.
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN '2014-02-01' AND '2014-03-01'
Between keyword works exceptionally for a date. it assumes the time is at 00:00:00 (i.e. midnight) for dates.
Read the documentation.
http://www.postgresql.org/docs/9.1/static/functions-datetime.html
I used a query like that:
WHERE
(
date_trunc('day',table1.date_eval) = '2015-02-09'
)
or
WHERE(date_trunc('day',table1.date_eval) >='2015-02-09'AND date_trunc('day',table1.date_eval) <'2015-02-09')
Suppose I have the following query:
select customer_name, origination_date
where origination_date < '01-DEC-2013';
I would like to select all customers that have an origination date older than 30 days. Is there a way in SQL (oracle, if specifics needed) to specify it in a more dynamic approach than manually entering the date so that I don't need to update the query every time I run it?
Thanks!
Sure try something like this:
select customer_name, origination_date where
origination_date >= DATEADD(day, -30, GETUTCDATE());
This basically says where the origination_date is greater or equal to 30 days from now. This works in Microsoft SQL, not sure but there is probably a similar function on Oracle.
in Oracle, when you subtract dates, by default you get the difference in days, e.g.
select * from my_table where (date_1 - date_2) > 30
should return the records whose date difference is greater than 30 days.
To make your query dynamic, you parameterize it, so instead of using hard coded date values, you use:
select * from my_table where (:date_1 - :date_2) > :threshold
If you are using oracle sql developer to run such a query, it will pop up a window for you to specify the values for your paramteres; the ones preceded with colon.