Amex SAS interview question

Amex sas  interview question

1.How will you combine  two  datasets using multiple SET statement and   with MERGE statement?  Explian  with  an  example?

2.   What  is  difference  between SAS Formats / Informats.

3. What is   difference between  @  trailing and @@   trailing?  explain  with  example?

4.     Give  an  example   where  you  will  prefer  to  use  DATA _NULL_?

5. How  will  you     assign  first.VAR and last.VAR to the BY group variable on unsorted data?
6. Write  sas code   to  delete duplicate observations?
7. What is the Program Data Vector (PDV)? Will  PDV  used   during  Proc  sql   data  creation?

8. What   difference between  SAS/ACCESS and SAS/CONNECT?
9.  What   difference between  SCAN   and SUBSTR function?