Query Entity filter isnull for date and time field

Question

Hi All, 
 I have scenario where i am using a query entity, 
 in this i have a date and time field. out of which the values of the 2 rows present are value of Now() and null 
 When i am trying to filter them like 
 a!queryFilter( 
 field:"date", 
 operator:"is null" 
 ) 
 it is not differentiating the results and it is giving me the entire set. 
 Am I going wrong anywhere on this, 
 TIA:) 
 Harsha

Dastagiri Dudekula · Answer

When you query filter on the field using is null, field must be null it should not be empty or updated by "". 
 Here I am searching for the entity where lastModifiedDate is null. 
 rule!SPB_LMS_QE_getXXXXDetails( filters: a!queryFilter(field:"lastModifiedBy", operator:"is null") ) 
 Following figures represent Appian cloud null visual representations 
 This will return the result. 
 This will not return the result because it has empty value. 
 To get the details make the field Null in the DB or update the field via write/update DB table