I have a scenario to cast string date into date format. But the date string is not in a straight format, so the conversion throws error. So what I tried is
set dateformat dmy
before the casting in sql and it worked without any issue.
But the trouble is I need this to implement in a view or function. But the disappointing part, function or view doesn't support set dateformat with which it says as side effecting operator
So how can I specify the date format of the given string before casting in a function or view?
The third parameter of CONVERT() allows to provide a format type.
Assuming your SET DATEFORMAT DMY I take you've to deal with dates like "1/2/2000", meaning the first of February in 2000.
Try this:
DECLARE #d VARCHAR(100)='1/2/2000';
SELECT CONVERT(DATE,#d,104)
The 104 is the German type with a 4-digit year. If this does not fit your needs, you can follow the link to find a better suiting format.
If you need further help, please provide samples of your actual dates.
Hint: You should always store a value in a column with the appropriate type. Storing dates as strings will make things slow and opens a lot of error sources...
As Damien wrote in his comment to the question, ideally you should not mess around with string representations of datetime in the first place - you should be using proper data types - and since you asked about creating a view, it can only mean that somewhere in your database there's a datetime value stored as a string.
The solution to this situation is to change the way you are storing this value - use DateTime2 for datetime values, Date for date-only values, or Time for time-of-day values.
Further reading - Aaron Bertrand's Bad habits to kick : choosing the wrong data type
Assuming you can't change the database design, read the rest of this answer.
You can't use set dateformat on a view or a function, but you can use convert instead of cast to change the string representation of a datetime value into an actual datetime value, assuming the string representation has one of the supported date formats (there are quite a few of them, so usually it shouldn't be a problem).
If your string representation of the datetime is in a format that is not supported by the built in convert function, you might need to do some extra work in the form of string manipulation to either change it into a supported format, or (in the harder case) separate the string representation to parts and then use datetimefromparts.
If you could provide the actual format you are using in your string representation of the datetime format I can probably edit this answer to show you exactly how to do it.
SELECT CONVERT(varchar(10),CAST('07/01/2018' AS DATE),23)
Result
2018-07-01
Not sure what you mean by, "date string is not in a straight format". Examples will help.
Have you tried parsing, instead of casting?
SELECT
TRY_PARSE(thedate AS datetime) as justParse
,TRY_PARSE(thedate AS datetime USING 'en-US') as parseUS
,TRY_PARSE(thedate AS datetime USING 'en-GB') as parseGB
,try_cast(thedate as date) as tryCast
FROM (values
('07/01/2018')
,('01/07/2018')
,('07 jan 2018')
,('jan 07 2018')
,('Monday, 7 January 2019')
)d(thedate)
Related
I have a wrong date in the database 2022-10-14 12:59:00 , I want to change it to 2022-14-10 12:59:00. Is there a direct convert function I could use, or do I have to split and put the date correctly. Just trying to get some ideas to do this the easy way. I tried the convert functions but I guess the original date as to be corrected first is it?
You can use the CONVERT() function to go from a date type to a string with a particular "style". There are styles for different presentation formats to represent the different date presentation formats around the world.
To make this work, the data needs to be in a date type, not just a string. (or you can convert from a string type to a date type, then convert back to a string).
Date style descriptions
I have a value in SQL that represents a date, but it of type nvarchar. The value of the date is in the format:
dd/mm/yyyy hh:mm
I need to present this column via a view to a CCure 800 database in DATETIME format. I expected to use CAST/CONVERT; however, when using this, the following error is returned:
Msg 242, Level 16, State 3, Line 1
The conversion of a varchar data type to a datetime data type resulted in an out-of-range value.
Please stop storing dates as strings, and especially as Unicode strings. Are you concerned that some future version of our calendar will have umlauts, pound signs, hieroglyphics, or Mandarin instead of numbers?
Store dates as dates. That is what those data types are for. In addition to not having to worry about invalid interpretations, you also get all of the benefits of things like DATEPART and DATEADD, and you don't have to worry about anyone stuffing nonsense into the column (anything from 31/02/2012 to 'I don''t want to enter a real date'...
In the meantime, you just need to use a style number with CONVERT (this won't work reliably with CAST):
SELECT CONVERT(DATETIME, '13/06/2013 09:32', 103);
To make it work with CAST, you could set your LANGUAGE or DATEFORMAT settings accordingly, but you can't do this inside a view, and it makes the code very brittle anyhow IMHO.
SET DATEFORMAT DMY;
SELECT CAST('13/06/2013 09:32' AS DATETIME);
Or
SET LANGUAGE BRITISH;
SELECT CAST('13/06/2013 09:32' AS DATETIME);
By a very wide margin, I prefer the additional control CONVERT gives you, and almost unilaterally change all instances of CAST to CONVERT, even when this control is not needed, for consistency (why use CAST in some cases, and CONVERT when you need it, when you can just use CONVERT always?).
EDIT
To identify the garbage data that has snuck into your table because of a bad data type choice, do this (and then fix the data or, better yet, fix the data type so this doesn't happen again):
SET DATEFORMAT DMY;
SELECT date_column FROM dbo.table_name WHERE ISDATE(date_column) = 0;
I know that it is possible to reformat the DateTime data type of the current date and time by using select convert. However, I havent been able to find a method to reformat an existing column (DateTime data type) to: hh:mm:ss yyyy/mm/dd. Or even better, I would like to reformat it to show time only. I dont want to simply convert to time data type because I am working with a chart that accepts either Date or Date time. But what I really want to display on that specific axis of the chart is time. Is there any way to reformat DateTime to my requirements? Thanks.
SQL Server's convert function can take an optional style argument depending upon the datatype. This is how you can get a datetime converted to a string in a variety of formats. For example, try running:
select convert(varchar(30), getdate(), 108) -- returns hh:mi:ss
You can replace getdate() in this example with a column name as well.
There are many styles available, as shown in the documentation.
Note that you will be returning a varchar, so you may want to sort by the original column's datatype.
You can use SET DATEFORMAT but this will change all DateTime's on your SQL Server. You can do some custom formatting, but it will convert the DateTime into a VarChar, so you won't be able to treat it as a DateTime.
SET DATEFORMAT: http://msdn.microsoft.com/en-us/library/ms189491.aspx
I'm not sure if you will be able to use the format you're asking about, though.
Does SQLs built-in DateTime type has any merits over nvarchar type?
If it were you , which one would you use?
I need to store dates in my SQLServer database and I'm curious to know which one is better and why it is better.
I also want to know what happens if I for example store dates as string literals (I mean nvarchar )? Does it take longer to be searched? Or they are the same in terms of performance ?
And for the last question. How can I send a date from my c# application to the sql field of tye DateTime? Is it any different from the c#s DateTime ?
You're given a date datetype for a reason, why would you not use it?
What happens when you store "3/2/2012" in a text field? Is it March 2nd? Is it February 3rd?
Store the date in a date or datetime field, and do any formatting of the date after the fact.
EDIT
If you have to store dates like 1391/7/1, your choices are:
Assuming you're using SQL Server 2008 or greater, use the datetime2 data type; it allows dates earlier than 1753/01/01 (which is what datetime stops at).
Assuming you're using SQL Server 2005 or earlier, store the dates as Roman calendar dates, and then in your application, use date/time functions to convert the date and time to the Farsi calendar.
Use the correct datatype (date/datetime/datetime2 dependant on version and requirement for time component).
Advantages are more compact storage than storing as a string (especially nvarchar as this is double byte). Built in validation against invalid dates such as 30 February. Sorts correctly. Avoids the need to cast it back to the correct datatype anyway when using date functions on it.
If I'm storing a DateTime value, and I expect to perform date-based calculcations based on it, I'll use a DateTime.
Storing Dates as strings (varchars) introduces a variety of logistical issues, not the least of which is rendering the date in a proper format. Again, that bows in favor of DateTime.
I would go with the DateTime since you can use various functions on it directly.
string wouldn't be too much of a hassle but you will have to cast the data each time you want to do something with it.
There is no real performance variance while searching on both type of fields so going with DateTime is better than strings when working with date values.
you must realise the datetime datatype like other datatypes is provided for a reason and you should use the datatype that represents your data clearly.. Besides this you gain all the functionalities/operations that are special to the datetime datatype..
One of the biggest gains is correct sorting of data which will not be possible directly if you use nvarchar as your datatype.. Even if you think you dont need sorting right now there will be a time in the future where this will be useful.
Also date validation is something that you will benefit from. There is no confusion of the dateformat stored i.e dd/mm or mm/dd etc..
There is lot discussed about the subject. There is good post on the SQLCentral forum about this particular subject DateTime or nvarchar.
In short, nvarchar is twice as longer as datetime, so it takes more space and on the long range, any action affecting it will be slower. You will have some validation issues and many more.
How can I retrieve a record based on a Date property? I'm trying:
WHERE Meetings.[MDate] = '16/12/2011'
which is the format I use but I get :
"Data type mismatch in criteria expression"
Problem solved: It should have been:
WHERE Meetings.[MDate] = 16/12/2011
No quotation marks.
For where clauses use
columnName = #mm/dd/yyyy#
You'll want to use the SQL date format: '#2011-12-16#'
Use the cast to DATETIME function, CDATE(), which will honour the machine's regional settings. That said, it still a good idea to use an unambiguous date format and the ISO 8601 format is a good one.
Also note that Access doesn't have a date data type: its sole temporal data type is DATETIME and, as its name suggests, always has a time element accurate to one second time granule, even if that time happens to be midnight. Therefore, it is a good idea to always include a time value to one second time granule in all DATETIME literals e.g.
WHERE Meetings.MDate = CDATE('2011-12-16 00:00:00');
Another advantage to the above is that the Access UI will not attempt to reformat the DATETIME literal because it is held as a string.