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.
Related
I'm trying to INSERT date variable into my SQL server.
The input format I'm trying to insert is: dd-mm-yyyy
And my SQL server column (which defined as type DATE) expect mm-dd-yyyy.
My PC date format is dd-mm-yyyy.
The error msg:
Conversion failed when converting date and/or time from character string.
Questions:
Why is the expected format mm-dd-yyyy and not dd-mm-yyyy?
How can I make the INSERT command work with this or another date format?
Thanks.
The format that your PC uses for dates doesn't matter when passing literal string for dates, the language setting for the LOGIN you are using to connect to SQL Server does. As the value is being interpreted as MM-dd-yyyy this very likely means that your language setting is (American) ENGLISH.
If, therefore, you are the only person that uses that LOGIN you may well want to change the language of your LOGIN to be appropriate for yourself. Most of the European languages, including BRITISH English (because the British don't speak English Microsoft? 😒) use the format dd-MM-yyyy.
Really, however, what you should be doing is using an unambiguous date format, of which there are only 2 in SQL Server, regardless of the language setting and data type. Those 2 formats are yyyyMMdd and yyyy-MM-ddThh:mm:ss.nnnnnnn. If you are always using the newer date and time data types (so not datetime or smalldatetime), then yyyy-MM-dd( hh:mm:ss.nnnnnnn) is also unambiguous, however, as it's language specific for the older data type then I don't normally recommend it's use.
Storage wise, date and time data types don't have a format, so your column isn't "expected" a value in the format MM-dd-yyyy, as it doesn't retain the "format data" that the value was passed in. Again, the only reason why a value like 13-12-2020 is working is because your language setting, which uses mdy for date interpretation.
Two things really,
Firstly, you can control the expected date format for each connection. Before issuing the insert statement, do set dateformat dmy; or set dateformat mdy; as appropriate.
Secondly, it's always advisable to work with dates in the ISO format of YYYYMMDD, so if you insert the data '20210314' it will always be treated correctly.
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)
I have a view in SQL Server 2012 and there is a column of containing dates×. I have been trying to convert the date column as '20/10/2018 18:00' format (no second) by using this feature and lots of approaches on Stackoverflow and other web sites:
FORMAT(StartDate, 'dd.mm.yyyy hh:mm')
However, as the data type of this column is Varchar (String) rather than DateTime, I encountered some problems in C# side and I want to perform this conversion on the database side without changing the data type of the generated format). Is there any way to achieve this?
SQL Server doesn't have a "date format" per se. The formatting of datetime fields is only performed when presenting the datetime to an output - that is, when converting it to a string.
There is a default format for presentation that is controlled by the server's collation setting. However, internally the date is stored as a numeric value (actual format varies by type, as datetime and datetime2 have different internal formats), and that value has no associated formatting.
You can store your date without seconds by using a smalldatetime field, or by manipulating the input data to trim off the seconds value. But, unless you store your date as a string, which is absolutely not recommended, you will not be able to save an output format different from the default collation-driven format in a datetime field.
I would migrate that column to a datetime (or some variant) if possible. Alternatively if that would affect too many things, you could make a computed column on the table which converts the string date you have to a datetime. That way the database doesn't have to care about the formatting at all; it just works with the proper DateTime data type.
If neither of those is an option, you can just pas the string to C# and use DateTime.TryParse() to convert it to a C# DateTime object.
In either case, it's preferable to work with the date as a DateTime up until the very last minute where you need to format it for display somewhere.
I work in T-SQL but have been given some Oracle PL-SQL for review on a Project.
Within the code there are Multiple WHERE clauses that do comparison of a Field of DataType = DATE against Strings which hold a "date".
ex:
WHERE to_date(mytable.mydatefield) > '23-OCT-2015'
OR
WHERE mytable.mydatefield > '23-OCT-2015'
Q1: Since "mydatefield" is already defined as a DATA type, isn't doing a "to_date" unnecessary?
Q2: Will Oracle do an implicit conversion on the '23-OCT-2015' and convert it to a date for comparison? I seem to remember encountering this before and comparing DATES to STRINGS caused issues?
Am I incorrect about that? If not can someone give me an example that I can use as evidence that it would not work?
A1: In general yes, but take the way Oracle handles implicit type conversions into account. The To_Date function around the mydatefield column expects a string input, so Oracle implicitly converts mydatefield to a string with a format matching the NLS_DATE_FORMAT session setting (which defaults to DD-MON-RR). Once converted to a string the To_Date function then converts it back to a date again using the current NLS_DATE_FORMAT setting. The newly reconstituted date is then compared to the string '23-OCT-2015', but since dates and strings aren't directly comparable the string value gets implicitly converted to a date using the current NLS_DATE_FORMAT setting. Depending on the value of the NLS_DATE_FORMAT setting, the first implicit conversion is likely to lose information specifically any time portion AND the original century, since the default NLS_DATE_FORMAT uses only a two digit year RR and no time component.
A2: Possibly, but it's best not to rely on it.
Both relations are poor programming for a couple of reasons. First they both are affected by implicit type conversions from dates to strings (or vice versa). Second they are both attempting to compare dates with strings in a non canonical form. As such 10-DEC-15 is less than 23-OCT-2015 because 1 is less than 2. Also note the difference in the number of digits representing the year since the default NLS_DATE_FORMAT uses a two digit year.
The correct method would be to compare the date column (possibly truncated) to a date string explicitly converted to a date
WHERE mytable.mydatefield > TO_DATE('23-OCT-2015', 'DD-MON-YYYY')
OR with truncation:
WHERE trunc(mytable.mydatefield) > TO_DATE('23-OCT-2015', 'DD-MON-YYYY')
which removes the time component of the date field.
Q1: According to Oracle, the first parameter of to_date() is a char value. Using it like to_date(date_value) you will force an implicit cast of date_value to char and then wrapping it again in a date value.
Q2: The server will do an implicit conversion from the string '23-OCT-2015' to a date value but based on database parameters which can differ from various servers(DEV vs PROD for example) so you should not rely on them. An example of correct usage would be WHERE mytable.mydatefield > to_date('23-OCT-2015','dd-MON-yyyy')
You should always use to_date/to_char to make sure you are using the correct format. Please see this answer for a more detailed explanation: Comparing Dates in Oracle SQL
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.