SQL Syntax Reference : PUBLIC
 
PUBLIC
Remarks
You can include the PUBLIC keyword in the FROM clause to revoke the Create Table right from all the users to whom the right was not explicitly assigned.
Include a FROM clause to specify the group or user from whom you are revoking rights. You can specify a single name or a list of names, or you can include the PUBLIC keyword to revoke access rights from all users whose rights are not explicitly assigned.
Examples
To assign access rights to all users in the dictionary, include the PUBLIC keyword to grant the rights to the PUBLIC group, as in the following example:
GRANT SELECT ON Course TO PUBLIC
This statement assigns the Select right on the Course table to all users defined in the dictionary. If you later revoke the Select right from the PUBLIC group, only users who are granted the Select right explicitly can access the table.
The following statement includes the PUBLIC keyword to grant the Create Table right to all the users defined in the dictionary:
GRANT CREATETAB TO PUBLIC
See Also
GRANT
REVOKE