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2.04 NULL behaviour |
Tue, Aug 24 2010 10:30 AM | Permanent Link |
Uli Becker | Hi,
<< You can now specify whether you want ANSI-SQL standard NULL behavior (the default), or non-ANSI-SQL NULL behavior where NULLs are comparable with normal operators (=,<>,>,<,BETWEEN, etc.) and NULL values are treated like an empty version of the containing value's data type. >> Does that mean that I can use: select * from MyTable where MyValue = NULL instead of select * from MyTable where coalesce(MyValue,'') = '' IOW: is "=Null" now the same as "=''"? Uli |
Tue, Aug 24 2010 11:12 AM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Uli,
<< Does that mean that I can use: select * from MyTable where MyValue = NULL instead of select * from MyTable where coalesce(MyValue,'') = '' IOW: is "=Null" now the same as "=''"? >> Not exactly. This change does not make NULL=<EmptyString>, it simply makes NULL usable with operators that normally it isn't usable with due to the standard. You still have to have NULL=NULL in order for the result to be True. For example, with the ANSI-standard behavior: SELECT * FROM MyTable WHERE MyStringColumn=NULL causes an error. With the non-standard behavior, this statement will return all rows where MyStringColumn *is actually NULL*, but not any rows where MyStringColumn is an empty string. IOW, the non-standard behavior does not make ElevateDB start working like DBISAM did with respect to string columns. It does, however, make it behave like DBISAM in terms of allowing NULLs to be used directly with comparison operators other than IS/IS NOT NULL. -- Tim Young Elevate Software www.elevatesoft.com |
Tue, Aug 24 2010 11:37 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Tim
I read this "and NULL values are treated like an empty version of the containing value's data type" and thought woopee back to a good approach. I was waiting until I could do some testing because I was sure Santa wasn't due just yet Roy Lambert |
Tue, Aug 24 2010 11:40 AM | Permanent Link |
Uli Becker | Roy,
> I read this "and NULL values are treated like an empty version of the containing value's data type" and thought woopee back to a good approach. I thought exactly the same. Thinking of you as well. Uli |
Wed, Aug 25 2010 7:22 AM | Permanent Link |
Tim Young [Elevate Software] Elevate Software, Inc. timyoung@elevatesoft.com | Roy,
<< I read this "and NULL values are treated like an empty version of the containing value's data type" and thought woopee back to a good approach. >> "Empty" in that statement means "not present", or NULL. I should have used the words "blank string" in my previous message to avoid confusion. Just remember that this feature does not change the core behavior of a NULL, only how NULLs can be used with comparison operators. -- Tim Young Elevate Software www.elevatesoft.com |
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