I currently have the date format 2016-11-23 16:47:21.007 and I am trying to convert it with this SQL:
update user_table set login_date = CONVERT(datetime,login_date,120)
So that I only get 2016-11-23 16:47:21 but it's currently just staying as the same format.
Am I missing something?
Your current requirement is mainly a presentation need. Since your login_date is already stored as a datetime, there is no need to change anything internally in your database.
When you need to present the login_date without milliseconds, then go ahead and call CONVERT as you were:
SELECT CONVERT(varchar(19), login_date, 120) AS login_date_no_millis
FROM yourTable
But there is no need to do the UPDATE you showed us in your question.
Altering the column to datatype datetime2(0) will mean milliseconds aren't stored. If you're certain you don't need them.
Equally, casting it to datetime2(0) in your select will do the same in the presentation level whilst maintaining the milliseconds in the database if required. Also means that unlike cast/convert to varchar, it's still a datetime value rather than a string if that makes a difference to the app.
Related
I think I've read just about every thread on this topic and none of them are solving my problem.
First of all, the database I'm working with has all date fields set to a varchar data type, which drives me insane because I constantly have to cast or convert whenever I'm working with any queries involving dates.
The query I'm working with at the moment is supposed to pull a list of medical patients who all have a certain diagnosis, but that diagnosis has to have been given before a certain date. Here's what I've got.
SELECT DISTINCT
pd.PatientID,
pd.PatientName,
pmh.DateOfOnset
pmh.DiagnosisCode
FROM PatientDemographic pd JOIN PatientMedicalHistory pmh ON pd.PatientID = pmh.PatientID
WHERE pmh.DiagnosisCode = '401.1'
AND CAST(pmh.DateOfOnset as Date) > CAST('12/31/2014' as Date)
I'm getting an error that says "Conversion failed when converting date and/or time from character string." It's telling me the error is on Line 1 though (the SELECT DISTINCT line) so that's not really helpful and I'm not sure what I need to fix.
As I mentioned, the DateOfOnset field has a varchar data type, and I need to find any of those dates that came before the end of December, 2014. I've tried to remedy this error by trying different combinations of the CAST statements -- I even tried including a cast on the date field in the SELECT statement, and I'm still getting the same error.
I was working on another query earlier that required me to find all patient appointments from within a certain time frame, and for that query, I had my WHERE clause set up like:
WHERE Cast(VisitDate as Date) BETWEEN CAST('01/01/2014' as Date) AND CAST('12/01/2014' as Date)
...and it worked perfectly fine. Since I've got my current query set up virtually the same way, I'm not sure why I'm getting that conversion error.
You have wrong dateformat:
SET DATEFORMAT dmy;
SELECT CAST('12/31/2014' as Date);
--Conversion failed when converting date and/or time from character string.
You could set it to mdy before executing your query.
SET DATEFORMAT mdy;
SELECT CAST('12/31/2014' as Date);
LiveDemo
or use CONVERT with style 101:
SET DATEFORMAT dmy;
SELECT CONVERT(DATE,'12/31/2014',101)
If you really need to store DATE as VARCHAR use at least culture independent type like ISO-8601.
SET DATEFORMAT dmy;
SELECT CAST('20140201' as Date);
-- 01.02.2014
SET DATEFORMAT mdy;
SELECT CAST('20140201' as Date)
-- 01.02.2014
It sounds like SQL is not able to convert the stored strings into dates. This would explain why CAST(pmh.DateOfOnset as Date) fails where Cast(VisitDate as Date) does not--the latter might not have any mis-formatted dates.
Best-case solution is to convert your table columns to the proper datatypes. Second-best case, add columns containing the proper datatypes, and convert the data over; you'd have to fix any existing bad data, as well as convert data on the fly as it's loaded (yuck). Another option, add a calculated column, though you'll have problems with the afore-mentioned invalid dates. (What version of SQL do you have? Later versions have the isdate function, which might help here.)
If modifying tables is not an option, you're probably stuck writing queries that have to assume some of the data is invalid (bad format).
What are the implications of using SQL Server's DateTime2 with a precision of 0 to represent a date rather than the built in Date field.
In either case, my concern is to prevent accidental time entries, but are there storage or performance considerations I should take note of?
DateTime2(0) will store datetime with no decimal values i.e YYYY-MM-DD hh:mm:ss
SELECT CONVERT(DateTime2(0) , GETDATE())
RESULT: 2015-04-06 20:47:17
Storing data just as dates will only store dates i.e YYYY-MM-DD without any time values.
SELECT CONVERT(Date , GETDATE())
RESULT: 2015-04-06
If you are only interested in dates then use DATE data type.
DATETIME2 will use 6 bytes for precisions less than 3 and DATE will use 3 bytes.
Date is half the size of DATETIME(0) hence it will also perform better since sql server will process less data and will save disk space as well.
It won't work. According to MSDN the minimum size of Datetime2 is six bytes and will contain hh:mm:ss so it can, and will, contain a time component (default of midnight). As other responders have noted you must use a date type to guarantee that not time portion is saved and will occupy three bytes.
https://technet.microsoft.com/en-us/library/bb677335%28v=sql.105%29.aspx
Just a reminder which I ran into myself when I converted a couple of DATETIME2(0) columns to DATE to make sure it aligned better with the value in the column (date only).
When using DATE you cannot use things like SELECT MyDate + 1 FROM.. or WHERE MyDate>0 while when using DATETIME2 you can, at least not in MS-SQL. Ofcourse IMHO it doesn't make any sense why DATETIME2 will allow you to do it and DATE not.
I have a date format 2011-01-06T06:30:10Z in Excel.I want to just load the date part into a table from excel.How do I get the date part from it.
i.e. 2011-01-06
Thanks
Try this:
select cast(TO_TIMESTAMP_TZ(REPLACE('2011-01-06T06:30:10Z', 'T', ''), 'YYYY-MM-DD HH:MI:SS TZH:TZM') as date) from dual
I think, some more explanation is needed.
Loading data into database is one part, and displaying it after fetching is another part.
If you have loaded the data into database, then all you need to do is use TRUNC. It will truncate the time portion and will display only the date portion.
A DATE always has a datetime part together. TIMESTAMP is an extension to the DATE type. And what you see the date looks like is not the way it is stored in database. The format is for we human beings to understand. A date is stored in 7 byte in internal format.
More information Based on OP's question via comments
NEVER store a DATE as VARCHAR2 datatype. A date is not a string literal. Oracle provides lot of FORMAT MODELS to display the datetime the way you want. Sooner or later, you will run into performance issues due to data conversion. Always use explicit conversion to convert a literal to a perfect DATE to compare it with other date value.
I need to get a SQL query to output the date from a datetime field in the format Mmm dd yyyy hh:mm AM/PM. The best aproach I've been able to come up with so far is:
SELECT Left(
Convert(
nvarchar(30),
SWITCHOFFSET(
CAST(datetime1 as datetimeoffset),
'-05:00'
),
0
),
LEN(
Convert(
nvarchar(30),
SWITCHOFFSET(
CAST(datetime1 as datetimeoffset),
'-05:00'
)
)
)-11
)
However, a) it's ugly! I feel like this should be simpler than that; and b) I think going to have to change my query when Daylight savings time comes back.
The source data is a sharepoint calendar, so I can't simply change the datatype to datetimeoffset.
Any ideas?
Thanks,
Steve
As a general principal you should not be using SQL to format data into something presentable for the front end. You should be getting a DateTime type back, and using code on the format to change it. What if a future requirement comes in to support DD/MM/YYY? You'll need a separate query. It's better to let the front end format it for that.
With that in mind, store 2 pieces of data in the database. 1) DateTime as a UTC value 2) The current user's timezone (not offset)
The reason you store timezone and not offset is because of all the rule involved with DST. For example, the days that DST starts end aren't fixed in stone. They are set for a country each year, but that schedule can change, and that's a bad reason to need to update your code (unless you're writing a timezone library.)
Then once you have these two pieces of data, you retrieve the date, and the timezone, and construct a new object in the server that allows you to convert the time in the DB to the local time.
Am I missing something, or is it simply:
Convert(nvarchar(30), DATEADD(Hour, -5, datetime1), 100)
That should add -5 hours to datetime1, then convert it into the format you were specifying.
I do agree that you should try to deal with timezones instead of offsets whenever possible.
I am seeeing my dates are stored in database in this format for a column (datetime datatype) 2011-01-14 10:15:41.787 i.e YYYY-MM-DD way . How could I make the default storage in YYYY-DD-MM format . Do I need to set that for all the DBS, or I can set it for single DB and how ?
I have the column in datetime datatype, right now it is saving as
2011-01-14 10:15:41.787 , my question is how can I set the db to store it as
2011-14-01 10:15:41.787
That is the crux of the confusion. Just because SQL Server Management Studio displays a datetime column in that format does not mean that it is stored AS TEXT YYYY-MM-DD hh:mm:ss.zzz. It is stored as binary, something like 0000101000001010..
Your dates are stored in SQL Server as a series of bytes (bits really) that make up some numeric value that is an offset from 1900-01-01. There is no inherent format the the dates. What you are referring to is that SSMS by default shows [display] datetime columns as YYYY-MM-DD hh:mm:ss.zzz. If you use a front-end programming tool, that too may impose a default [display] format unless you have asked for another one.
There is absolutely NO way to make SSMS show datetime data in another format through options or configuration. If you must, you would have to update the SQL query to convert the datetime column to a VARCHAR column containing the TEXTual equivalent in a particular format. That may be useful in SSMS, but would be bad when used as a data source to front-end GUI/web apps - since the values are not datetime and cannot be used for interval calculation, graphing, bound to date controls etc.
See this example of displaying time (getdate()) as YYYY-DD-MM, a very unusual format. Notice the date field/variable has to be used twice:
select stuff(convert(char(7), getdate(), 120), 5, 0, '-' + convert(char(2), getdate(), 3))
DATETIMEs are stored internally as two 4 byte integers, so firstly you are seeing a formatted representation for the UI - it's not actually stored in a particular date/time format as such.
e.g. if you insert just a date like "2010-01-01" then it will still hold the time element: 2010-01-01 00:00:00.000
If you're only interested in the DATE part, then you can format the DATETIME for output either in your front-end code or via your query:
e.g.
SELECT CONVERT(VARCHAR(8), GETDATE(), 121)
So even if the DATEs you insert contain a time, that will be ignored when returned. You could also ensure you only insert dates without the time specified - you need to handle that in whatever code is doing the INSERTs. e.g. from .NET, instead of passing in DateTime.Now you could pass in DateTime.Now.Date.
In SQL Server 2008, there is a DATE datatype which is there to only store a DATE (without time) which is really what you want in this kind of scenario.