I have question about the hands on practice in chapter 4, Oracel 11g: Question 9 is that produce a list of information about all existing...

I have question about the hands on practice in chapter 4,  Oracel 11g: SQL. Question 9 is that "produce a list of information about all existing constraints on the store_reps table". I tried some ways, but all of them give the result of "no rows selected". But I did add some constraints in the previous question, and I did not log off SQLPLUS during this process.