Given that your language is limited and '||' concatanates stings I would guess at SQL. 
CASE WHEN LOWER(foo) = UPPER(foo) THEN 'No Alpha' ELSE 'Alpha' END

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However in some SQL varients you can use translate (has an effect like tr///) 
CASE WHEN INSTR(TRANSLATE(foo, 
  'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', 
  'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'),    
'X')>0
 THEN 'Alpha' ELSE 'No Alpha' END

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Or Even 
CASE WHEN LENGTH(TRANSLATE(foo, 
  '#abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', 
  '#'))<>LENGTH(foo)
 THEN 'Alpha' ELSE 'No Alpha' END

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Hope it Helps UnderMine

In reply to Re: Challenge - Creative Way To Detect Alpha Characters by UnderMine
in thread Challenge - Creative Way To Detect Alpha Characters by Limbic~Region

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