topic Choice Stage - Cannot Compare Unknown in Product Forum

Choice Stage - Cannot Compare Unknown

BrentonCarr — Tue, 16 Jul 2019 20:40:00 GMT

Hi all,

What exactly does "Cannot compare unknown" error message mean within a choice stage? I have built a process that runs a SQL query and sends the results to a collection with two columns. Column X is text, Column Y is a number. In my choice stage, I have 6 conditions that loop through the collection and perform a calc action if any one of them is true. All of the choices that are a single condition work fine (ie. X = "word") but on more complex ones involving numbers (X = "word" AND Y>1) I get that error. I get the same error if I have Y>1 alone as a condition as well. It seems as if the expression only considers 1 and 0 to be valid values, anything else returns that error. Where am I going wrong?

Thanks!

RE: Choice Stage - Cannot Compare Unknown

nobu — Wed, 17 Jul 2019 03:36:00 GMT

Thank you for posting.

> but on more complex ones involving numbers (X = "word" AND Y>1) I get that error. I get the same error if I have Y>1 alone as a condition as well.
Based on this information, the problem should be in the value of "Y". Please check the following points.

Which value was set in Y
What data type was set in the value Y

> What exactly does "Cannot compare unknown" error message mean within a choice stage?
I couldn't find the error message in our previous cases. If you share the process/object for us to replicate the same error, I will take a look at this issue a little bit more.

Regards,

Nobu

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Nobuhiro Tokushige
Product Specialist
Blue Prism
Australia/Sydney
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RE: Choice Stage - Cannot Compare Unknown

John__Carter — Wed, 17 Jul 2019 09:15:00 GMT

Could be that the SQL results contain NULL values, and Blue Prism doesn't have the concept of NULL.

Suggest changing collection Column Y to text data type and the SQL to use ISNULL(FieldA, '') to ensure null values are never returned.

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John Carter
Professional Services
Blue Prism
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