I have a table and need to verify that a certain column contains only dates. I'm trying to count the number of records that are not follow a date format. If I check a field that I did not define as type "date" then the query works. However, when I check a field that I defined as a date it does not.
Query:
SELECT
count(case when ISDATE(Date_Field) = 0 then 1 end) as 'Date_Error'
FROM [table]
Column definition:
Date_Field(date, null)
Sample data: '2010-06-27'
Error Message:
Argument data type date is invalid for argument 1 of isdate function.
Any insight as to why this query is not working for fields I defined as dates?
Thanks!
If you defined the column with the Date type, it IS a Date. Period. This check is completely unnecessary.
What you may want to do is look for NULL values in the column:
SELECT SUM(case when Date_Field IS NULL THEN 1 ELSE 0 end) as 'Date_Error' FROM [table]
I also sense an additional misunderstanding about how Date fields, including DateTime and DateTime2, work in Sql Server. The values in these fields are not stored as a string in any format at all. They are stored in a binary/numeric format, and only shown as a string as a convenience in your query tool. And that's a good thing. If you want the date in a particular format, use the CONVERT() function in your query, or even better, let your client application handle the formatting.
ISDATE() only evaluates against a STRING-like parameter (varchar, nvarachar, char,...)
To be sure, ISDATE()'s parameter should come wrapped in a cast() function.
i.e.
Select isdate(cast(parameter as nvarchar))
should return either 1 or 0, even if it's a MULL value.
Hope this helps.
IsDate takes a character string or exression that yeilds a character string as it's argument
The problem is this method ISDATE() only admits arguments of type datetime and smalldatetime within the "time" types, so it won´t work if you are using date type.
Also if you use date as type for that field, you won´t have to check the information there because it won´t admit other type of field.
You shoul only check for null values in your column, that´s all.
Related
I am trying to cast a column as smalldatetime from varchar. There are some rows containing errors, how can I find them?
SELECT
PA.EAR_TAG
,ISNULL(B.DISPOSAL_DATE, H.DISPOSAL_DATE) as HB_Date
,Y.[DATE OF MOVEMENT] as Y_Date
,DATEDIFF(DAY, ISNULL(B.DISPOSAL_DATE, H.DISPOSAL_DATE), cast(Y.[DATE OF MOVEMENT] as smalldatetime))
FROM
DairyTelomere.dbo.PROJECT_ANIMALS AS PA
LEFT JOIN
Langhill.dbo.YOUNG_STOCK_BULL AS B ON Pa.EAR_TAG = B.EAR_TAG
LEFT JOIN
Langhill.dbo.YOUNG_STOCK_HEIFER AS H ON PA.EAR_TAG = H.EAR_TAG
LEFT JOIN
DairyTelomere.dbo.Young_Stock_culls AS Y ON PA.EAR_TAG = Y.Ear_Tag
The error I get is:
Msg 242, Level 16, State 3, Line 1
The conversion of a varchar data type to a smalldatetime data type resulted in an out-of-range value.
I know that if the column was in a date format I could check it by using ISDATE() but unfortunately I can't change the column type (don't have permissions).
Any ideas will be greatly appreciated.
you can use the isdate to get a list of all the ones that are not converting for you. You dont need to change the column type to use this so i am confused by your statement
if the column was in a date format I could check it by using ISDATE() but unfortunately I can't change the column type (don't have permissions)
Will help more if you can clarify but this query should get you a list of rows that have bad date values.
select table.date_as_varchar
from table
where isdate(table.date_as_varchar) = 0
adding to #workabyte answer you can also try using TRY_PARSE, TRY_CAST OR TRY_CONVERT, all of them return NULL if the conversion failed, that way you can know wich rows caused the error.
TRY_PARSE
as the documentation says:
Use TRY_PARSE only for converting from string to date/time and number
types. For general type conversions, continue to use CAST or CONVERT.
Keep in mind that there is a certain performance overhead in parsing
the string value.
Usage example:
SELECT TRY_PARSE(your_date AS DATETIME USING 'es-ES') as date
FROM your_table
es-ES is a culture parameter,different culture paramaters yield different results in your conversions, you can find the full list of parameters in the documentation
TRY_CONVERT
as the documentation says:
TRY_CONVERT takes the value passed to it and tries to convert it to
the specified data_type. If the cast succeeds, TRY_CONVERT returns the
value as the specified data_type; if an error occurs, null is
returned. However if you request a conversion that is explicitly not
permitted, then TRY_CONVERT fails with an error.
Usage example:
SELECT TRY_CONVERT(DATETIME,your_date,103) as date
FROM your_table
The 103 being the style/format of the date you are converting, here you can find a list of the formats avaliable
TRY_CAST
as the documentation says:
TRY_CAST takes the value passed to it and tries to convert it to the
specified data_type. If the cast succeeds, TRY_CAST returns the value
as the specified data_type; if an error occurs, null is returned.
However if you request a conversion that is explicitly not permitted,
then TRY_CAST fails with an error.
Usage example:
SELECT TRY_CAST(your_date AS DATETIME) as date
FROM your_table
I want to use Like operator in a column of datetime. The values of the column is as follows:
2013-08-31 17:54:52.000
2013-08-31 17:54:52.000
My query is as below:
SELECT * FROM table where created_date Like '%54%'
It works fine. but when I search for '%52%' instead of '%54%', it gives me nothing. (It is working when I search till the minutes, but when I search for seconds or milli seconds it does not work.)
I have looked at the following url and it is working
SQL LIKE Statement on a DateTime Type
I want to know the reason, why this is happening and how like operator works with datetime type column.
I think it would be a better idea to use the DATEPART operator of SQL SERVER to extract the portion of date.
And example could be like:-
SELECT * FROM table
where DATEPART(minute,created_date)=54
EDIT:-
I want to know the reason, why this is happening and how like operator
works with datetime type column.
Actually there is no direct support given by SQL Server for LIKE operator for DATETIME variable but you can always cast the DATETIME to a VARCHAR and then try to use the LIKE operator as you want.
On a side note:-
MSDN says:-
DATEPART can be used in the select list, WHERE, HAVING, GROUP BY and
ORDER BY clauses.
In SQL Server 2012, DATEPART implicitly casts string literals as a
datetime2 type. This means that DATEPART does not support the format
YDM when the date is passed as a string. You must explicitly cast the
string to a datetime or smalldatetime type to use the YDM format.
The 'LIKE' operator and any regular expression operators provided by other databases are used to process text values. A date is definitely not a text value, it is a separata type by itself.
It makes little sense to apply a text operator to a non-text type (like int or DATETIME or DATETIMEOFFSET), which is why you can't use LIKE on dates in any database. First of all, the values are not stored as text but in an implementation-specific binary form.
Then, while you can use LIKE on a specific text representation of a date, eg using CAST you have to absolutely certain what that representation is. Different locales display dates differently, with year first, year last, month first or last or whatever. What would you search against?
Moreover, what is 54? 54 minutes, 54 seconds or 654 milliseconds?
The only sensible solution is to use DATEPART to check specific parts of a date, or the BETWEEN operator to check for ranges.
I have to run column checks for data consistency and the only thing that is throwing off my code is checking for character lengths for dates between certain parameters.
SEL
sum(case when ( A.date is null or (character_length(A.date) >8)) then 1 else 0 end ) as Date
from
table A
;
The date format of the column is YYYY-MM-DD, and the type is DA. When I run the script in SQL Assistant, I get an error 3580 "Illegal use of CHARACTERS, MCHARACTERS, or OCTET_LENGTH functions."
Preliminary research suggests that SQL Assistant has issues with the character_length function, but I don't know how to adjust the code to make it run.
with chareter length are you trying to get the memory used? Becuase if so that is constant for a date field. If you are trying to get the length of the string representation i think LENGTH(A.date) will suffice. Unfortanatly since teradata will pad zeros on conversions to string, I think this might always return 10.
UPDATE :
Okay so if you want a date in a special 'form' when you output it you need to select it properly. In teradata as with most DBs Date are not store in strings, but rather as ints, counting days from a given 'epoch' date for the database (for example the epoch might be 01/01/0000). Each date type in teradata has a format parameter, which places in the record header instructions on how to format the output on select. By default a date format is set to this DATE FROMAT 'MM/DD/YYYY' I believe. You can change that by casting.
Try SELECT cast(cast(A.date as DATE FORMAT 'MM-DD-YYYY') as CHAR(10)) FROM A. and see what happens. There should be no need to validate the form of the dates past a small sample to see if the format is correct. The second cast forces the database to perform the conversion and use the format header specified. Other wise what you might see is the database will pass the date in a date form to SQL Assitant and sql assitant will perform the conversion on the application level, using the format specified in its own setting rather then the one set in the database.
I have a date column with dates stored as strings, such as 20120817. Unfortunately, the text form field that populates this column is free text, so I cannot guarantee that an occasional "E" or "whatever" shows up in this column. And more than a few already have.
What I need to do is convert the string column into a date column. Of course the convert will reject the random string characters. Is there any way to create a derived column that will not only convert the strings but exclude the non-date convertible strings?
If there were no non-date convertible strings in the table, the following would work:
ADD [convertedDate] AS CONVERT(DATE, [stringDate], 102)
And it does work perfectly in a test table I created. But when I introduce other non-convertible strings, I receive the dreaded "Conversion failed when converting date and/or time from character string" error for obvious reasons.
Is there a function that will catch non-convertible elements that I can add on to this derived column code? Or is a view or function the only - or best - way to handle this? I played around with IsDate() with little luck.
Thank you!
There's a function called ISDATE(date), maybe you can use it in a CASE statement or in the WHERE part of the query... It depends on how you're doing it, maybe something like this
ADD [convertedDate] AS CASE WHEN ISDATE([stringDate]) = 1 THEN CONVERT(DATE,[stringDate], 102) ELSE NULL END
If you're using SQL Server 2012 you can make use of the try_convert function
http://msdn.microsoft.com/en-us/library/hh230993.aspx
It will work normally if the conversion succeeds but return null if the conversion fails
ADD [convertedDate] AS TRY_CONVERT(DATE, [stringDate], 102)
This should give you some ideas...
DECLARE #date1 varchar(50)
DECLARE #date2 varchar(50)
SET #date1 = '20120101'
SET #date2 = 'e20120101'
SELECT
ISDATE(#date1),
ISDATE(#date2),
CASE WHEN ISDATE(#date1) = 1 THEN CONVERT(SMALLDATETIME,#date1) END,
CASE WHEN ISDATE(#date2) = 1 THEN CONVERT(SMALLDATETIME,#date2) END
Whenever the value is null for this query
SELECT ISNULL(someDateTime,'')
FROM someTable
the result is
someDateTime
------------
1900-01-01 00:00:00.000
I want it to be "No", so if I run this:
SELECT ISNULL(someDateTime,'No')
FROM someTable
then there's this error:
Conversion failed when converting datetime from character string.
How to do it? Thanks in advance!
The result of the expression will need to be a single type. If you want a character string (and you do, since 'No' is not a DateTime), you'll need to convert the datetime to such a string:
SELECT ISNULL(cast(someDatetime as varchar(20)), 'No') FROM someTable
As others have suggested, though, code like this smells bad, and you may want to pass the null to a client component and do the conversion there.
isnull() is trying to convert the second argument to the datatype of the field you specify in the first argument.
If you are going to be returning a string you need to cast the DateTime field to a string type so that isnull() can work properly - see Michael Petrotta's answer for a way to accomplish this.
You're still selecting a DateTime column, and so the result of that expression still needs to be a DateTime value rather than a string. To suggest an appropriate work-around, we'll need to know more about what you're really trying to do with this data.
You can't as such directly. It's easier to trap NULL in the client and change it to "no" there.
However, you could use a token value such as "17530101" which is a valid datetime, or CONVERT SomeDateTime first to varchar.
Otherwise, we need more info on why etc
In your Update Stored Proc: Update your previous date value to a new Null value:
.Parameters.AddWithValue("#Date_Value", Nothing).IsNullable = True