SQL ,PLSQL , Unix

1. Write an SQL statement to delete all duplicate rows in a table.    Give all possible SQL statements that can be used to delete duplicate rows effectively. 2. Consider the following table ID Name Role ManagerId MGR6002 RajeshKumar Manager MGR1001 TM1001 Sridevi Associate MGR6002   TM1002 John Sr.Associate MGR6002 TM1008 Rexan Associate MGR6002   MGR6003 Amruta Manager MGR1001 MGR6004 Justin Manager MGR1001   MGR1001 Ravikumar GPM VCH1001 TM1003 Linton Associate MGR6004   TM1003 Kavitha Sr.Associate MGR6004 TM1005 Sailu Analyst MGR6002   TM1006 Sami Sr.Associate MGR6001       Write an SQL to print employee list hierarchically     Ex output. Rajeshkumar John Rexan Sailu Amruta Justin Linton Kavitha 3. Write the SQL statement to obtain nth salary of employees. 4. Wha...