How should I structure this AMPscript to display 1 value if empty and other if not?

Question

%%[ 

/*Set Dynamic Image URL for Hours Field */
IF not empty (@Business_Hours__c ) THEN
  SET @HoursImgURL = "URL1" 
ELSE 
  SET @HoursImgURL = "URL2"
ENDIF

]%%

or should I use:

IF Business_Hours__c == NULL THEN?

Answer 1

I'd suggest reviewing the value you're relying on in your conditional:

%%[ 

var @business_hours__c, @hoursImgURL 
set @business_hours__c = AttributeValue("business_hours__c")

output(concat("<br>business_hours__c: ", @business_hours__c))

IF not empty(@business_hours__c) THEN
  SET @HoursImgURL = "URL1" 
ELSE 
  SET @HoursImgURL = "URL2"
ENDIF

output(concat("<br>HoursImgURL: ", @HoursImgURL ))

]%%