连接写法

--建立表A
create table cici.aa
(name char(64) not null enable,
 id number (*,0) not null enable,
 primary key (id)  enable--tablespace "CICI"
 );

 --建立表BB
 create table cici.bb(
    name char(64) not null enable,
    id number (*,0) not null enable,
    aid number (*,0),
    primary key (id)  enable,--tablespace "cici"
    constraint "fk_b2_a" foreign key (aid)
    references cici.aa (id) enable
 ); 

insert into aa (name ,id) values (‘cici‘,1);
insert into aa (name ,id) values (‘titi‘,2);
insert into aa values (‘mimi‘,3);

insert into bb (name,id,aid ) values (‘vivi‘,1,1);
insert into bb (name,id,aid ) values (‘lili‘,2,1);
insert into bb (name,id,aid ) values (‘kiki‘,3,1);
insert into bb (name,id,aid ) values (‘uiui‘,4,2);
insert into bb (name,id,aid ) values (‘oioi‘,5,2);
commit;

 /*BEGIN*/
    select count(*)
    from aa
   where exists (select bb.aid from bb where bb.aid = aa.id); --等值连接
  
  select count(*)
    from bb
   where exists (select aa.id from aa where bb.aid = aa.id); --等值连接
  
  select count(*) from aa, bb where bb.aid = aa.id; --   等值连接
  
  select count(*) from aa right join bb on aa.id = bb.aid; --   右连
  select count(*) from aa ,bb where aa.id(+) = bb.aid; 
  
  select count(*) from aa left join bb on aa.id = bb.aid; --    左联接
  select count(*) from aa,bb where aa.id = bb.aid(+);
 /*END*/