grant select on database demo to user

I find myself with long lists of tables
 grant select on xx_tax to user; grant select on xx_trip to user; grant select on xx_foo to user;

Is there a way to grant to all tables, with a single grant?  I know how
to do it in mysql, but not postgres.  As close as I get it:

#grant select on database demo to user
ERROR:  invalid privilege type SELECT for database

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