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Message Posted: Wed, 19 Mar 2008 @ 20:22:33 GMT


     
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Subj:   Re: Comparing blanks and Nulls
 
From:   Michael Larkins

Sounds like you have some pretty inconsistent source data that might better be scrubbed before you load it into a production table. Additionally, you have not specifically told us, but to have a zero length I am assuming that the string must be varchar. Also as pointed out previously, a zero length character string is not the same as a NULL. So have you considered:

     ,case when char(blank_column) = 0 then '*' else blank_column) end
     .
     .
     .
     MINUS ALL

     ,coalesce(nullable_column,'*')
     .
     .
     .

If need be, you can also check for the NULL in the same case statement. If you have similiar inconsistencies in the second table you can impliment the coalesce using a case and compare for multiple values there as well.


Hope this helps,

Michael Larkins
Certified Teradata Master
Certified Teradata SQL Instructor



     
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