Oracle - grant privileges to all users

I need to grant privileges to all users, I can do:

GRANT select on table TO user1;
GRANT select on table TO user2;
...

But there are many users. How ca开发者_如何学运维n I grant this privilege to all users at once?

I tried:

GRANT select on table TO ALL;

But that doesn't work.

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grant select on table to public;

But be careful when you do that -- make sure it's what you really want to do.

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You should use roles. Grant permission to roles. grant roles to users.