Hello Veena,
thanks a lot for your help.
I my case I had to check a NVARCHAR field if it is initial.
But in if() statements in HANA studio attribute view it doesn't work with ' '.
I tried out another workaround, where the result in if() statement is integer and it worked 
.
What I did was to use if(strlen(<mynvarcharfield>) = 0, ...), that means if the return value of strlen() = 0 the if condition is fulfilled, otherwise (when <mynvarcharfield> has a value in it) strlen() is not equal 0, since the return value is the number of the string lengths in bytes.
Thank you for your support.
Best regards,
Christian