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Compare string to date in sql

Posted on 2011-09-21
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Last Modified: 2012-05-12
I have the query

select * from DateTTable
where dataField like '%j%'

this query return all results, however dataField  is only consists of date

I am I missing something

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Question by:erikTsomik
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Expert Comment

by:venk_r
ID: 36575843
Is the dateField declared as DATETIME  datatype?
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Author Comment

by:erikTsomik
ID: 36576065
yes does declares as datetime
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venk_r earned 500 total points
ID: 36576107
Please don't handle datetime field as string values. You will not get the desired result.The 'like %%' clause are string related operators.
When you want query date field please use either 'between' clause or  else '>'  and '<' operators.

Something like this if you know the ranges

select * from DateTTable
where dataField between '01/01/2011' and '02/01/2011'

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Author Comment

by:erikTsomik
ID: 36576123
well it is easy with a range what if I do not have a range and the user just start typing the I wanto find all data in the database which matches this entry
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Expert Comment

by:venk_r
ID: 36576296
First thing they will not be able to enter character in a datetime field.The reason you re getting the result is because it does  ascii conversion internally.
if ou really want to apply like operator then convert the datefield into a string before fetching.


select * from DateTTable
where convert(varchar(20),dataField) like '%%'

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Expert Comment

by:Anthony Perkins
ID: 36577707
>>The 'like %%' clause are string related operators.<<
You may want to double check that.  See this section from SQL Server BOL:
Using Operators with Date and Time Data Types
The relational operators (<, <=, >, >=, <>), comparison operators (=, <, <=, >, >=, <>, !<, !>) and logical operators and Boolean predicates (IS NULL, IS NOT NULL, IN, BETWEEN, EXISTS, NOT EXISTS, and LIKE) are supported for all the date and time data types.


I am not saying it is appropriate to use in this case, but to make a blanket statement that LIKE only supports character data is plain wrong.
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Author Comment

by:erikTsomik
ID: 36577754
SO what is the conclusion I know that like can be used it just an interpretation of like statement but when i provide one later it returns records which should NOT be there
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Expert Comment

by:Anthony Perkins
ID: 36577817
If you use it correctly, than it should be fine. As you can see in the following example:

DECLARE @dat date

SET @dat = GETDATE()

SELECT      @dat,
      CASE
            WHEN @dat LIKE '2011-08%' THEN 'GETDATE() LIKE 2011-08%'
            ELSE 'GETDATE() NOT LIKE 2011-08%'
      END,
      CASE
            WHEN @dat LIKE '2011-09%' THEN 'GETDATE() LIKE 2011-09%'
            ELSE 'GETDATE() NOT LIKE 2011-09%'
      END
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Expert Comment

by:venk_r
ID: 36577859
You are right acperkins. May be I may  have misunderstood about the like operator usage.

But my point to wrikrsomik is
You have given the below statement

select * from DateTTable
where dataField like '%j%'

This should result all the month's data containing Jan,July and June.Anything apart from that should be filtered.
If that doesnt work at all may be try the below statement.It should the return all the months containing 'J' in it.

select * from DateTTable where month (dataField ) in(1,6,7)

 
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