I want to run a query monthly to look for records from the previous month. The where clause will be greater or equal to the 1st day of the month and less or equal to the last day. The difficultly I am having is the dates are stored as numbers in a column with a numeric data type. The format being used is yyyymmdd. We are currently manually changing the where clause, so e.g. show me any records with dates >=20201001 to <=20201031, but we need to automate this process. I have tried a few ways to try and solve this but need some guidance.
So far I've tried:
select concat( CONCAT(cast((Year(DATEADD(month, -1, getdate()))) as numeric),cast((Month(DATEADD(month, -1, getdate()))) as numeric)),'01')
Returns error message operand data type numeric is invalid for concat operator. Works in separate query window returning format yyyymmdd.
SELECT DATEADD(mm, DATEDIFF(mm, 0, (DATEADD(month, -1, getdate()))), 0)
Returns error message arithmetic overflow error converting expression to data type date time. Works partly in separate query window but returns yyyy-mm-dd hh:mi:ss:ms
Any help would be greatly appreciated.
Thanks
The real solution is fix the design; don't store dates in a datatype other than a date and time data type.
What you can do, however, is convert the value of GETDATE() to a numerical value of the same format:
SELECT ...
FROM ...
WHERE NumericalDate >= CONVERT(varchar(8),DATEADD(DAY, 1, EOMONTH(GETDATE(),-1)),112)
AND NumericalDate < CONVERT(varchar(8),DATEADD(DAY, 1, EOMONTH(GETDATE())),112)
For today, this would return rows where NumericalDate is in November 2020 (specifically on or after 20201101 and before but not on 20201201).
Note, I don't "bother" to CAST/CONVERT the varchar to a Numerical data type, as it'll be implicit cast due to data type precedence.
You can use artihmetics like so:
where dates >= year(getdate()) * 10000 + month(getdate()) * 100 + 1
and dates < year(dateadd(month, 1, getdate())) * 10000 + month(dateadd(month, 1, getdate())) * 100 + 1
Compare the month and forget the days.
BETWEEN 20201000 and 20201099 finds the same rows as your example >=20201001 to <=20201031
That means that you do not have to figure out how many days are in the month.
I'm looking to add in a condition to my already badly performing SQL code. I want to add in a filter where the date = yesterday (data type as INT).
For example
Select *
From table
Where Date = 20190930
How do I do this using GETDATE() - 1?
We need to be very clear about what data type you're using.
If you have a simple date value (no time component as part of the data type), things are pretty easy:
Select *
from table
where Date = DATEADD(day, -1, cast(current_timestamp as date))
If you have a DateTime or DateTime2 value, it's important to understand that all DateTime values have a time component that goes all the way down to milliseconds. This is true even when you expect the time component to always be at or near midnight. That can make straight equality comparisons difficult. Instead, you almost always need check within a specific range:
Select *
from table
where Date >= DATEADD(day, -1, cast(current_timestamp as date))
AND Date < cast(current_timestamp as date)
Here's your query.
Firstly, you need to cast your int date to a varchar before covenrting to datetime, to avoid an arithmetic flow error during conversion.
Secondly, you need to cast getdate() - 1 as date to truncate time to match your date field.
select *
from table
where cast((cast(date as varchar(8))as datetime) = cast(getdate() - 1 as date)
or
select *
from table
where cast((cast(date as varchar(8)) as date) = cast(dateadd(day,datediff(day,1,GETDATE()),0) as date)
I have been able to find a lot of information for getting a string representation of just the time from a datetime column like this one.
I need to get the time part out of a datetime in a way that I can do some math on it like adding it to another datetime. So a string representation of the time wont help me.
However I've only found one example that will extract the time as a numeric type value. I.e:
SELECT CAST(GETDATE() AS FLOAT) - FLOOR(CAST(GETDATE() AS FLOAT))
This method requires two casts though and I have to run this on over 10,000 rows. Is there anything similar to the dateadd method for extracting the date part from a datetime column i.e.:
select DATEADD(dd, DATEDIFF(dd, 0, getdate()), 0)
that I can use to get just the time out of a datetime column and return it as a decimal or datetime? Perhaps a solution that uses less casting?
I am using SQL Server 2000.
To get a datetime:
SELECT GetDate() - DateDiff(day, 0, GetDate());
-- returns the time with zero as the datetime part (1900-01-01).
And to get a number representing the time:
SELECT DateDiff(millisecond, DateDiff(day, 0, GetDate()), GetDate());
-- time since midnight in milliseconds, use as you wish
If you really want a string, then:
SELECT Convert(varchar(8), GetDate(), 108); -- 'hh:mm:ss'
SELECT Convert(varchar(12), GetDate(), 114); -- 'hh:mm:ss.nnn' where nnn is milliseconds
One way You can get the time in seconds is with:
select cast(datediff(second, DATEADD(dd, DATEDIFF(dd, 0, getdate()), 0), getdate())/(60*60*24.0) as datetime)
This calculates the time in seconds and then converts back to a datetime.
To get it as a decimal:
select datediff(second, DATEADD(dd, DATEDIFF(dd, 0, getdate()), 0), getdate())/(60*60*24.0)
Or use "ms" if you prefer millisecond precision.
Or, you can use the more readable:
select datepart(hh, getdate())/24.0+datepart(mm, getdate())/(24*60.0)+
datepart(ss, getdate())/(24*60*60.0)
I hope anyone can translate my abstract query.
I want to select * from TABLE where ( [MYDATETIMEROW] < (TODAY - 3 Days)).
Does I have to Convert, cast or use datepart or anything else?.. im confused.
Are there simple rules? I would'nt have problems to do that with linq but simple sql I learned just hardly.
Thank you and best regards.
In simple terms:
Select * from Table where MyDateTimeRow < dateadd(dd,-3,getdate())
But using getdate() will provide both a date and a time, experience says that this is unlikely to be exactly what you want - you might want to strip the time down and just consider the date portion
Select * From Table where MyDateTimeRow < dateadd(dd, datediff(dd, 0, getdate()) - 3, 0)
You want the DateAdd function to manipulate dates and the GetDate function to get the current date:
SELECT * FROM MyTable WHERE [MyDateTimeRow] < DateAdd(dd, -3, GetDate())
I'm trying to compare time in a datetime field in a SQL query, but I don't know if it's right. I don't want to compare the date part, just the time part.
I'm doing this:
SELECT timeEvent
FROM tbEvents
WHERE convert(datetime, startHour, 8) >= convert(datetime, #startHour, 8)
Is it correct?
I'm asking this because I need to know if 08:00:00 is less or greater than 07:30:00 and I don't want to compare the date, just the time part.
Thanks!
Your compare will work, but it will be slow because the dates are converted to a string for each row. To efficiently compare two time parts, try:
declare #first datetime
set #first = '2009-04-30 19:47:16.123'
declare #second datetime
set #second = '2009-04-10 19:47:16.123'
select (cast(#first as float) - floor(cast(#first as float))) -
(cast(#second as float) - floor(cast(#second as float)))
as Difference
Long explanation: a date in SQL server is stored as a floating point number. The digits before the decimal point represent the date. The digits after the decimal point represent the time.
So here's an example date:
declare #mydate datetime
set #mydate = '2009-04-30 19:47:16.123'
Let's convert it to a float:
declare #myfloat float
set #myfloat = cast(#mydate as float)
select #myfloat
-- Shows 39931,8244921682
Now take the part after the comma character, i.e. the time:
set #myfloat = #myfloat - floor(#myfloat)
select #myfloat
-- Shows 0,824492168212601
Convert it back to a datetime:
declare #mytime datetime
set #mytime = convert(datetime,#myfloat)
select #mytime
-- Shows 1900-01-01 19:47:16.123
The 1900-01-01 is just the "zero" date; you can display the time part with convert, specifying for example format 108, which is just the time:
select convert(varchar(32),#mytime,108)
-- Shows 19:47:16
Conversions between datetime and float are pretty fast, because they're basically stored in the same way.
convert(varchar(5), thedate, 108) between #leftTime and #rightTime
Explanation:
if you have varchar(5) you will obtain HH:mm
if you have varchar(8) you obtain HH:mm ss
108 obtains only the time from the SQL date
#leftTime and #rightTime are two variables to compare
If you're using SQL Server 2008, you can do this:
WHERE CONVERT(time(0), startHour) >= CONVERT(time(0), #startTime)
Here's a full test:
DECLARE #tbEvents TABLE (
timeEvent int IDENTITY,
startHour datetime
)
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 0, GETDATE())
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 1, GETDATE())
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 2, GETDATE())
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 3, GETDATE())
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 4, GETDATE())
INSERT INTO #tbEvents (startHour) SELECT DATEADD(hh, 5, GETDATE())
--SELECT * FROM #tbEvents
DECLARE #startTime datetime
SET #startTime = DATEADD(mi, 65, GETDATE())
SELECT
timeEvent,
CONVERT(time(0), startHour) AS 'startHour',
CONVERT(time(0), #startTime) AS '#startTime'
FROM #tbEvents
WHERE CONVERT(time(0), startHour) >= CONVERT(time(0), #startTime)
Just change convert datetime to time that should do the trick:
SELECT timeEvent
FROM tbEvents
WHERE convert(time, startHour) >= convert(time, #startHour)
if (cast('2012-06-20 23:49:14.363' as time) between
cast('2012-06-20 23:49:14.363' as time) and
cast('2012-06-20 23:49:14.363' as time))
One (possibly small) issue I have noted with the solutions so far is that they all seem to require a function call to process the comparison. This means that the query engine will need to do a full table scan to seek the rows you are after - and be unable to use an index. If the table is not going to get particularly large, this probably won't have any adverse affects (and you can happily ignore this answer).
If, on the other hand, the table could get quite large, the performance of the query could suffer.
I know you stated that you do not wish to compare the date part - but is there an actual date being stored in the datetime column, or are you using it to store only the time? If the latter, you can use a simple comparison operator, and this will reduce both CPU usage, and allow the query engine to use statistics and indexes (if present) to optimise the query.
If, however, the datetime column is being used to store both the date and time of the event, this obviously won't work. In this case if you can modify the app and the table structure, separate the date and time into two separate datetime columns, or create a indexed view that selects all the (relevant) columns of the source table, and a further column that contains the time element you wish to search for (use any of the previous answers to compute this) - and alter the app to query the view instead.
Using float does not work.
DECLARE #t1 datetime, #t2 datetime
SELECT #t1 = '19000101 23:55:00', #t2 = '20001102 23:55:00'
SELECT CAST(#t1 as float) - floor(CAST(#t1 as float)), CAST(#t2 as float) - floor(CAST(#t2 as float))
You'll see that the values are not the same (SQL Server 2005). I wanted to use this method to check for times around midnight (the full method has more detail) in which I was comparing the current time for being between 23:55:00 and 00:05:00.
Adding to the other answers:
you can create a function for trimming the date from a datetime
CREATE FUNCTION dbo.f_trimdate (#dat datetime) RETURNS DATETIME AS BEGIN
RETURN CONVERT(DATETIME, CONVERT(FLOAT, #dat) - CONVERT(INT, #dat))
END
So this:
DECLARE #dat DATETIME
SELECT #dat = '20080201 02:25:46.000'
SELECT dbo.f_trimdate(#dat)
Will return
1900-01-01 02:25:46.000
Use Datepart function: DATEPART(datepart, date)
E.g#
SELECT DatePart(#YourVar, hh)*60) +
DatePart(#YourVar, mi)*60)
This will give you total time of day in minutes allowing you to compare more easily.
You can use DateDiff if your dates are going to be the same, otherwise you'll need to strip out the date as above
You can create a two variables of datetime, and set only hour of date that your need to compare.
declare #date1 datetime;
declare #date2 datetime;
select #date1 = CONVERT(varchar(20),CONVERT(datetime, '2011-02-11 08:00:00'), 114)
select #date2 = CONVERT(varchar(20),GETDATE(), 114)
The date will be "1900-01-01" you can compare it
if #date1 <= #date2
print '#date1 less then #date2'
else
print '#date1 more then #date2'
SELECT timeEvent
FROM tbEvents
WHERE CONVERT(VARCHAR,startHour,108) >= '01:01:01'
This tells SQL Server to convert the current date/time into a varchar using style 108, which is "hh:mm:ss". You can also replace '01:01:01' which another convert if necessary.
I believe you want to use DATEPART('hour', datetime).
Reference is here:
http://msdn.microsoft.com/en-us/library/ms174420.aspx
I don't love relying on storage internals (that datetime is a float with whole number = day and fractional = time), but I do the same thing as the answer Jhonny D. Cano. This is the way all of the db devs I know do it. Definitely do not convert to string. If you must avoid processing as float/int, then the best option is to pull out hour/minute/second/milliseconds with DatePart()
I am assuming your startHour column and #startHour variable are both DATETIME; In that case, you should be converting to a string:
SELECT timeEvent
FROM tbEvents
WHERE convert(VARCHAR(8), startHour, 8) >= convert(VARCHAR(8), #startHour, 8)
below query gives you time of the date
select DateAdd(day,-DateDiff(day,0,YourDateTime),YourDateTime) As NewTime from Table
#ronmurp raises a valid concern - the cast/floor approach returns different values for the same time. Along the lines of the answer by #littlechris and for a more general solution that solves for times that have a minute, seconds, milliseconds component, you could use this function to count the number of milliseconds from the start of the day.
Create Function [dbo].[MsFromStartOfDay] ( #DateTime datetime )
Returns int
As
Begin
Return (
( Datepart( ms , #DateTime ) ) +
( Datepart( ss , #DateTime ) * 1000 ) +
( Datepart( mi , #DateTime ) * 1000 * 60 ) +
( Datepart( hh , #DateTime ) * 1000 * 60 * 60 )
)
End
I've verified that it returns the same int for two different dates with the same time
declare #first datetime
set #first = '1900-01-01 23:59:39.090'
declare #second datetime
set #second = '2000-11-02 23:56:39.090'
Select dbo.MsFromStartOfDay( #first )
Select dbo.MsFromStartOfDay( #second )
This solution doesn't always return the int you would expect. For example, try the below in SQL 2005, it returns an int ending in '557' instead of '556'.
set #first = '1900-01-01 23:59:39.556'
set #second = '2000-11-02 23:56:39.556'
I think this has to do with the nature of DateTime stored as float. You can still compare the two number, though. And when I used this approach on a "real" dataset of DateTime captured in .NET using DateTime.Now() and stored in SQL, I found that the calculations were accurate.
TL;DR
Separate the time value from the date value if you want to use indexes in your search (you probably should, for performance). You can: (1) use function-based indexes or (2) create a new column for time only, index this column and use it in you SELECT clause.
Keep in mind you will lose any index performance boost if you use functions in a SQL's WHERE clause, the engine has to do a scan search. Just run your query with EXPLAIN SELECT... to confirm this. This happens because the engine has to process EVERY value in the field for EACH comparison, and the converted value is not indexed.
Most answers say to use float(), convert(), cast(), addtime(), etc.. Again, your database won't use indexes if you do this. For small tables that may be OK.
It is OK to use functions in WHERE params though (where field = func(value)), because you won't be changing EACH field's value in the table.
In case you want to keep use of indexes, you can create a function-based index for the time value. The proper way to do this (and support for it) may depend on your database engine. Another option is adding a column to store only the time value and index this column, but try the former approach first.
Edit 06-02
Do some performance tests before updating your database to have a new time column or whatever to make use of indexes. In my tests, I found out the performance boost was minimal (when I could see some improvement) and wouldn't be worth the trouble and overhead of adding a new index.