• kdb+

  Referencing new column

  Posted by powerpeanuts on November 16, 2021 at 12:00 am

  For example:

  t:([] name:`Dent`Beeblebrox`Prefect; iq:98 42 126)

  select name, iq2:iq%100 from t where iq2>1

   

  I would like to reference the newly created “iq2” column in the where clause, but the above command fails. How to modify it to make it work?

   

  powerpeanuts replied 8 months, 1 week ago 3 Members · 2 Replies
• 2 Replies

• 

  davidcrossey

  Member

  November 16, 2021 at 12:00 am

  Hi powerpeanuts,

  You would need to add your new column first, before trying to use it in the where clause. For example:

  q)t:([] name:`Dent`Beeblebrox`Prefect; iq:98 42 126) 
  q)select name, iq2 from (update iq2:iq%100 from t) where iq2>1 
  name    iq2 
  ------------ 
  Prefect 1.26

  Thanks for posting your question on the KX Community. Great username too!

  Kind regards,

  David

• 

  cillianreilly

  Member

  November 16, 2021 at 12:00 am

  As David mentioned, you can’t reference iq2 before you create it. If your where clause isn’t too wieldy, you can just include that in the qsql query to create column iq2:

  q)select name,iq2:iq%100 from t where 1<iq%100 
  name    iq2 
  ------------ 
  Prefect 1.26

  This does the calculation twice, so be careful with particularly heavy where conditions.

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