9i: Check- constraint Upper(Column)

Hi newsgroup,

Is it possible to build a constraint, that ensures, that there are not 
more entries in a column, that look like
'Abc   ' -> trim(upper(..))='ABC'
'ABC'    -> trim(upper(..))='ABC'
'aBC '   -> trim(upper(..))='ABC'
?

Alternativ I could build a shadow column filled by a trigger that 
containes trim(upper(..)) and a check constraint on this, but it seems 
to me that there is a better way.

Thank you in advance
Andreas Mosmann

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