KB32599: No data is returned as a result of selecting a null element as the answer for a prompt in MicroStrategy Web

SYMPTOM:
When choosing a null element as the answer for an attribute element prompt defined in a report, Strategy Developer and Web generate different SQL. While Developer resolves the condition as "attribute ID is null," and returns a row, Web resolves the SQL as "attribute In List (''), resulting in no data returned.
 
STEPS TO REPRODUCE:

• Create a table with two columns and populate 3 rows. Make sure that one of the cell has a null.
  

• Create two attributes mapped to each column: Country and State. 
• Create a report with an attribute element list prompt defined with Country. Place both Country and State in the grid.
  

• Execute the report in Developer and select the null element as the answer for the prompt. 
  

• Confirm the following report SQL is generated and one row is returned:
   
  
  
  Sql
  
  select a11.COUNTRY COUNTRY,
  a11.STATE STATE
  from NULLTEST a11
  where a11.COUNTRY is null
  
  
   
  

• Execute the report in Web and select null element as the answer for the prompt as well.
  

• Confirm the following report SQL is generated and no data is returned:
   
  
  Sql
  select a11.COUNTRY  COUNTRY,
   a11.STATE  STATE
  from NULLTEST a11
  where a11.COUNTRY in ('')
  
  
   
    

 
CAUSE:
This is caused by use of null attribute IDs. Null attribute IDs are not supported in Strategy and are not guaranteed to work correctly in different places.
 
ACTION:
Replace the null attribute IDs with valid values.
 
WORKAROUND 1:
Define an attribute qualification prompt and select the "Is Null" operator to qualify on the attribute.