ALTER GROUP groupname ADD USER username [, ... ] ALTER GROUP
groupname DROP USER username [, ... ] ALTER GROUP groupname
RENAME TO newname ALTER GROUP changes the attributes of a user
group. This is an obsolete command, though still accepted for
backwards compatibility, because groups (and users too) have
been superseded by the more general concept of roles. The first
two variants add users to a group or remove them from a group.
(Any role can play the part of either a "user" or a "group" for
this purpose.) These variants are effectively equivalent to
granting or revoking membership in the role named as the
"group"; so the preferred way to do this is to use GRANT or
REVOKE. The third variant changes the name of the group. This is
exactly equivalent to renaming the role with ALTER ROLE. The
name of the group (role) to modify. Users (roles) that are to be
added to or removed from the group. The users must already
exist; ALTER GROUP does not create or drop users. The new name
of the group. Add users to a group: