What is Sysdba?

[alan.almeida]

Good morning, I'm new to the forum and Oracle, I have started to study and work with PLSQL, I know that the doubt is very basic, but what is Sysdba? Is a user, or group? I already looked on the internet and I can not find anything that sages my doubt, for example: I connect by SQL Developer with a user I created called admin, I tried to create a synonym for a table, and I could not, for lack of privileges, there I I change the connection to sysdba, by face already appears a lot of tables that did not exist before, then I managed to create the synonym for the table, only if I go back to the connection without the sysdba I can not see the synonym, nothing I Crio as sysdba appears when I am without sysdba, and vice versa, very confusing this issue of users in Oracle, if anyone can clarify me I thank you.

[adrianoturbo]

Brother, when we are talking about Sysdba, we are talking about administrative privileges within the bank.
SYSDBA consists of a privileged system, effectively allowing the SYS user to have all the permissions within the bank.
What can you do the SYS user with the sysdba privileges system inside the bank?
- Make Startup and Bank Shutdown operations;
- Make changes to the bank It is in the modes: Open, Mount, Backup and Changes of character sets:
- Database creation;
- database drop;
- Creation of spfile;
- Amendment of Archivelogs;
- Bank recovery;
- Inclusion and restriction of privileged sessions.