"SYS" USER

“SYS” is a magic User?Answer: Yes, but why? Why everyone recommended to “don’t use sys” user for database activities.Because:1. SYS (SYSDBA) is super and top most privileged user in Oracle Database.2. We Can’t LOCK user SYS account.Consider:SQL> conn sys as sysdbaEnter password:Connected.SQL> alter user scott account lock;User altered.SQL> discDisconnected from Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 - PrSQL> conn scott/tigerERROR:ORA-28000: the account is lockedSQL> conn sys as sysdbaEnter password:Connected.SQL> alter user SYS account LOCK;User altered.SQL> discDisconnected from Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 - PrSQL> conn sys as sysdbaEnter password:Connected.SQL>3. We Can’t set TRANSACTION READ ONLY for SYS user.Consider:SQL> conn scott/tigerConnected.SQL> create table X as select * from all_objects where rownum =1;Table created.SQL> set TRANSACTION READ ONLY;Transaction set.SQL> delete from X;delete from X*ERROR at line 1:ORA-01456: may not perform insert/delete/update operation inside a READ ONLYtransactionSQL> conn sys as sysdbaEnter password:Connected.SQL> create table X as select * from all_objects where rownum =1;Table created.SQL> set TRANSACTION READ ONLY;Transaction set.SQL> delete from X;1 row deleted.SQL> commit;Commit complete.4. When we use SYS (SYSDBA) user.1. When we can’t do database work with ANY OTHER user except SYS (SYSDBA)1. Database Full Recovery (FULL, UNTIL CANCEL, UNTIL TIME, UNTIL SCN)2. Change Database Character Set 3. Create Database4. Drop DatabaseNote: For above work we must need SYSDBA (SYS) user.When we use SYS (SYSOPER) user1. Database Full Recovery (Not incomplete recovery)2. Perform Database SHUTDOWN/STARTUP3. Create SPFILE4. Alter database OPEN/MOUNT/BACKUP5. Includes the RESTRICTED SESSION privilege6. Alter database ARCHIVELOGNote: For above work we should use SYSOPER (SYS) user. And except above work if we want to perform normal database activity operation then Create Separate User and Grant DBA role and use that user.