It is not possible to write the following boolean condition in SQL:
SELECT ... FROM ... WHERE set1 CONTAINS set2 


You can see that the condition that "set1 constains set2" is equivalent to:
set1 CONTAINS set2 <==> set2  set1 = EMPTY 
Therefore:
SELECT ... FROM ... WHERE set1 CONTAINS set2 // Pseudo code !!! 
SELECT ... FROM ... WHERE set1 is a SUBSET of set2 // Pseudo code !!! 