Question on loading null values

[#1]

I recently took over an app that is using a perl script to pipe the data from the database to a text file.  For any null or undefined values from the db, the script gives the field a value of "-".  I know that null values are represented as "-" in Qlikview, but i have no idea why this script explicitly converts nulls to "-" in the data file.

My question:  is there risk to simply loading (if pipe is the delimiter) "||" instead of "|-|"?  Does Qlikview view that as being one and the same?  I want to switch over from text file loads to direct database loads, this is one of the differences i'm finding.

Thanks

Justin

[swuehl]

No, it's not the one and the same for QV. There is a difference between a value like '-' and NULL (and that's not only the case regarding QV), e.g. when counting field values.

If you have a close look into your app, you will probably find some places where there is taken care of the special char '-'.

But, you can probably adapt your app to handle also NULLs in your data model.

[#3]

Thanks.  There are actually many apps these qvd's are loaded into so i'd have to check all of them for logic.  What does a "-" mean when loaded to QV?  I know that it displays a "-" if there is no value in a chart for example, but i can't understand why anyone would want to load a "-" explicitly.

[rbecher]

If you have a literal hyphen "-" in your source file which represents a NULL value I would suggest to dump it in the source like you already have considered: empty value as "||" where pipe is delimiter instead of "|-|"

However, there is no risk to load NULL values directly from a database.