I'm trying to find all the saturdays between two dates (inclusive) without using a loop.
For example, April 1, 2021, to May 1, 2021 should return:
04-03-2021
04-10-2021
04-17-2021
04-24-2021
05-01-2021
You can use datename
select *
from Table
where Datename(dw,Datecolumn)='Saturday'
and DateColumn >= start and Datecolumn < End;
Alternatively, if you just want to generate a list on the fly, you can do
declare #StartDate date = '20210401', #EndDate date = '20210501';
select DateAdd(day, rn-1, #StartDate)
from (
select Row_Number() over (order by object_id) rn
from sys.columns
) d
where rn - 1 <= DateDiff(day, #StartDate, #EndDate)
and DateName(dw, DateAdd(day, rn-1, #StartDate))='Saturday';
This first generates a list of numbers in the inner query by utilising one of several possible system tables to select just a row number. This is essentially building a numbers / tally table on the fly, and it's usually a good idea to have a permanent table like this available (a single column of integers starting at 1 and going up to a squintillion or whatever you need). You can see how this works by just highlighting the inner query and running it (F5 in SSMS).
An out query selects from this and filters the row numbers to just the right sequential range for the number of days between the two specified dates. Again, you can check this by highlighting the entire query except for the last line, you'll see it generates the list of dates between the specified start and end dates inclusively.
Finally the and criteria extracts the name of the day for each date and further filters the list of dates based on the day's name.
Related
We need to create a report based on employee, say Kumar, logged 3 hours.
For example,
if a person is logged Hours in system for 1-1-2021. But he didn't log for 2-1-2021.
We have a join query to get the date and worked hours for each employee.
Our present report is like below (this is the screenshot from SSRS report)
But we need the missing dates also in the report. Abhishek has logged only from 4th Jan in the system. But we need rows above 4th Jan also in the report.
First name and last name should be in those columns in the new row. The hours worked should be 0 and other column values should be N/A or Null.
But here we need a query to get all dates in a month in the report whether the employee logged hours or not.() for not logged days)
This is the report that we want in SSRS.(i created this in excel)
How can i do that?
enter image description here
You are not able to force the missing dates with SSRS. To make this work correctly, you'll need to update your query to get all the dates in your date range and then LEFT JOIN your current data to the dates.
Add a INTO to your current report query put to put the data in a #TEMP_TABLE.
SELECT <CURRENT FIELDS>
INTO #TEMP_TABLE
FROM BLAH BLAH BLAH
Then Create a table of dates for your date range using a CTE with RECURSION.
DECLARE #START_DATE DATE = '01/01/2020' --THESE DATES SHOULD BE CHANGE TO USE PARAMETERS OF YOUR DATE RANGE
DECLARE #END_DATE DATE = '03/31/2021' --OR MIN/MAX FROM THE #TEMP_TABLE
;WITH GETDATES AS
(
SELECT #START_DATE AS THEDATE
UNION ALL
SELECT DATEADD(DAY,1, THEDATE) FROM GETDATES
WHERE THEDATE < #END_DATE
)
SELECT D.THEDATE, T.*
FROM GETDATES D
LEFT JOIN #TEMP_TABLE T ON D.THEDATE = T.DATE_WORKED
OPTION (maxrecursion 0)
This will return every date in THEDATE field with your current data in the other fields.
Sorry if this has been asked, but I didn't find anything when searching: I have a large table of ~100k rows in SQL Server. Within each row is a date range, which in many cases spreads across multiple months (and years to a lesser extent). The ranges are typically about 30-35 days however they usually don't start at the the 1st of the month. An example of a typical date range is 01/10/2017-02/11/2017.
I'm looking for the most efficient way to output the month with the most days within in that range as it's own column. I'm doing the same thing for the year
Right now I have the following in my query:
SELECT DISTINCT
a.START_DATE,
a.END_DATE,
cast(month(dateadd(day, datediff(day, a.Start_Date, a.End_Date)/2, a.Start_Date)) as tinyint) as Main_Month,
cast(year(dateadd(day, datediff(day, a.Start_Date, a.End_Date)/2, a.Start_Date)) as smallint) as Main_Year
FROM TABLE
The output from that query using the above date range example would give me:
Start_Date: 01/10/2017 End_Date: 02/11/2017 Main_Month: 1 Main Year: 2017
That method has worked alright, but it slows when being done for all rows in the table. Are there any more efficient alternatives that I can use for the Main_Month and Main_Year columns?
EDIT IN RESPONSE TO COMMENTS:
By "month w/ the most days within a date range", using my example range of 01/10/2017-02/11/2017, since that range contains 21 days in January and only 11 in February, the output I'd get for Main_Month is 1. Also since the year is 2017 throughout the range the output I'd get for Main_Year is 2017
For ties, I'd go with the 1st month containing the max # of days. In the example of, 6/20/2017 - 9/5/2017 I'd go with 7, since that is the 1st month with 31 days in the range
As discused in the comments above, this solution is not perfectly accurate, but it mirrors the accuracy of the original slower solution:
SELECT b.START_DATE, b.END_DATE, month(b.mid_point) as Main_Month, year(b.midpoint) as Main_Year FROM
(SELECT DISTINCT
a.START_DATE,
a.END_DATE,
dateadd(day, datediff(day, a.Start_Date, a.End_Date)/2, a.Start_Date) as mid_Point
FROM a) as b
You should be able to speed it up by making these two changes. First, only compute the datediff and dateadd once, then take it from the derived table to get the two fields you need. Next, don't bother with casting, since Month() and year() both do that for you. Were you able to see a speed difference with this method?
I think using CASE statements could be more efficient, and if you can avoid casting, like this:
, CASE WHEN datediff(day, a.Start_Date, a.End_Date) + 1 - DAY(a.END_Date) < DAY(a.END_DATE) THEN MONTH(a.End_Date)
ELSE MONTH(a.Start_Date) END AS Main_Month
, CASE WHEN YEAR(a.END_Date) = YEAR(a.Start_Date) THEN YEAR(a.Start_Date)
WHEN datediff(day, a.Start_Date, a.End_Date) + 1 - DAY(a.END_Date) < DAY(a.END_DATE) THEN YEAR(a.End_Date)
ELSE YEAR(a.Start_Date) END AS Main_Year
I have a column with values like '3rd-Wednesday', '2nd-Tuesday', 'Every-Thursday'.
I'd like to create a column that reads those strings, and determines if that date has already come this month, and if it has, then return that date of next month. If it has not passed yet for this month, then it would return the date for this month.
Expected results (on 4/22/16) from the above would be: '05-18-2016', '05-10-2016', '04-28-2016'.
I'd prefer to do it mathematically and avoid creating a calendar table if possible.
Thanks.
Partial answer, which is by no means bug free.
This doesn't cater for 'Every-' entries, but hopefully will give you some inspiration. I'm sure there are plenty of test cases this will fail on, and you might be better off writing a stored proc.
I did try to do this by calculating the day name and day number of the first day of the month, then calculating the next wanted day and applying an offset, but it got messy. I know you said no date table but the CTE simplifies things.
How it works
A CTE creates a calendar for the current month of date and dayname. Some rather suspect parsing code pulls the day name from the test data and joins to the CTE. The where clause filters to dates greater than the Nth occurrence, and the select adds 4 weeks if the date has passed. Or at least that's the theory :)
I'm using DATEFROMPARTS to simplify the code, which is a SQL 2012 function - there are alternatives on SO for 2008.
SELECT * INTO #TEST FROM (VALUES ('3rd-Wednesday'), ('2nd-Tuesday'), ('4th-Monday')) A(Value)
SET DATEFIRST 1
;WITH DAYS AS (
SELECT
CAST(DATEADD(MONTH,DATEDIFF(MONTH,0,GETDATE()),N.Number) AS DATE) Date,
DATENAME(WEEKDAY, DATEADD(MONTH,DATEDIFF(MONTH,0,GETDATE()),N.Number)) DayName
FROM master..spt_values N WHERE N.type = 'P' AND N.number BETWEEN 0 AND 31
)
SELECT
T.Value,
CASE WHEN MIN(D.Date) < GETDATE() THEN DATEADD(WEEK, 4, MIN(D.DATE)) ELSE MIN(D.DATE) END Date
FROM #TEST T
JOIN DAYS D ON REVERSE(SUBSTRING(REVERSE(T.VALUE), 1, CHARINDEX('-', REVERSE(T.VALUE)) -1)) = D.DayName
WHERE D.Date >=
DATEFROMPARTS(
YEAR(GETDATE()),
MONTH(GETDATE()),
1+ 7*(CAST(SUBSTRING(T.Value, 1,1) AS INT) -1)
)
GROUP BY T.Value
Value Date
------------- ----------
2nd-Tuesday 2016-05-10
3rd-Wednesday 2016-05-18
4th-Monday 2016-04-25
My Question
I am trying to write a stored procedure that retrieves the week numbers for the past X weeks and then inserts them into a temporary table.
So far I have been able to create the temporary table and return the contents (not very hard). However, my issue now lies with the inserting of the last X week numbers into my temporary table... Do I use a loop of some sort? If so, how do I do this?
Please note I cannot do a simple minus of the current week number because that could produce negatives if the current week number is less than X... The week number has to be calculated with DATEPART each time (I think).
What I have tried...
My code so far looks like this:
-- Declare the variables for the login totals
DECLARE #Current_Week_Number int
-- Get the current week number
SELECT #Current_Week_Number = DATEPART( wk, GETDATE())
-- Create the temporary table
CREATE TABLE #Number_Of_Logins (
Week_Number tinyint,
Number_Of_Logins int
)
-- Return the number of logins
SELECT * FROM #Number_Of_Logins
something like this?
declare #X int = 3
;with cte as (
select 0 as num
union all
select num + 1 from cte where num < #X - 1
)
select
datepart(wk, dateadd(wk, -num, getdate()))
from cte
sql fiddle demo
The query consists of 2 parts. Part 1 is recursive common table expression. Basically what I need here is to build a table of numbers from 0 to #X - 1, like this:
num
0
1
2
After that, I need to calculate date like current date, current date - 1 week, current date - 2 week - so I use dateadd() function (note minus before num, I want to substract weeks). And now I just need to calculate week number by datepart() function.
I have a Sales table:
id_item, quantity, date_time
What I need is to sum the items sold in a month and divide them by the days of the month from a selected period of months.
Example - The user selects the dates of Oct 1 to Dec 31. I need to show the items_sold/days_of_month:
Month Items sold Days of month Items/Day
Sep 25 30 0.83333
Oct 36 31 1.16
Dec 15 31 0.4838
I have to specify by Kind of item. the kind is obtained from another table called Items. I use dateformat dd/mm/yy.
select
month(date_time),
sum(quantity) / (select(datepart(dd,getdate())))
from
sales v
join items a on v.id_item=a.id_item
where
a.kind='Kind of Item'
and cast(Convert(varchar(10), date_time, 112) as datetime)
between '01/10/2012' and '31/12/2012'
group by
month(date_time)
My problem is selecting the days of the months, how can I select x number of months and divide the sum(quantity) of each month by the days of each?
I know this part of the code only selects the days of the current month:
(select(datepart(dd,getdate())))
Try this on for size:
DECLARE
#FromDate datetime,
#ToDate date; -- inclusive
SET #FromDate = DateAdd(month, DateDiff(month, 0, '20121118'), 0);
SET #ToDate = DateAdd(month, DateDiff(month, 0, '20121220') + 1, 0);
SELECT
Year = Year(S.date_time),
Month = Month(S.date_time),
QtyPerDay =
Sum(s.quantity) * 1.0
/ DateDiff(day, M.MonthStart, DateAdd(month, 1, M.MonthStart))
FROM
dbo.Sales S
INNER JOIN dbo.Items I
ON S.id_item = I.id_item
CROSS APPLY (
SELECT MonthStart = DateAdd(month, DateDiff(month, 0, S.date_time), 0)
) M
WHERE
I.kind = 'Kind of Item'
AND S.date_time >= #FromDate
AND S.date_time < #ToDate
GROUP BY
Year(S.date_time),
Month(S.date_time),
M.MonthStart
It will select any full month that is partially enclosed by the FromDate and ToDate. The * 1.0 part is required if the quantity column is an integer, otherwise you will get an integer result instead of a decimal one.
Some stylistic notes:
Do NOT use string date conversion on a column to ensure you get whole days. This will completely prevent any index from being used, require more CPU, and furthermore is unclear (what does style 112 do again!?!?). To enclose full date periods, use what I showed in my query of DateCol >= StartDate and DateCol < OneMoreThanEndDate. Do a search for "sargable" to understand a very key concept here. A very safe and valuable general rule is to never put a column inside an expression if the condition can be rewritten to avoid it.
It is good that you're aliasing your tables, but you should use those aliases throughout the query for each column, as I did in my query. I recognize that the aliases V and A came from another language so they make sense there--just in general try to use aliases that match the table names.
Do include the schema name on your objects. Not doing so is not a huge no-no, but there are definite benefits and it is best practice.
When you ask a question it is helpful to explain all the logic so people don't have to guess or ask you--if you know (for example) that users can input mid-month dates but you need whole months then please indicate that in your question and state what needs to be done.
Giving the version of SQL server helps us zero in on the syntax required, as prior versions are less expressive. By telling us the version we can give you the best query possible.
Note: there is nothing wrong with putting the date calculation math in the query itself (instead of using SET to do it). But I figured you would be encoding this in a stored procedure and if so, using SET is just fine.