ORA-01797: this operator must be followed by ANY or ALL

ISSUE:
sql statment didn't run with error ORA-01797

CAUSE:
equal operator = followed by multiple value like (1,2)

SOLUTION:
 a. change = to in
b. add any before multiple value like = any (1, 2)

reference:
 http://oraclequirks.blogspot.com/2008/06/ora-01797-this-operator-must-be.html