select a.id,b.online,a.nane from room a,online b where a.id=b.id and b.online>0
select table room.id table online.online table online.name from table room ,table online where table room.id=table online.id and table online.online>0哎一起学习
--两种写法(建议第二种) select A.id,B.online,A.name from A,B where A.id=B.id and B.online>0 select A.id,B.online,A.name from A inner join B on A.id = B.id where B.online > 0
from room a,online b
where a.id=b.id
and b.online>0
table room.id=table online.id and table online.online>0哎一起学习
select A.id,B.online,A.name
from A,B
where A.id=B.id and B.online>0 select A.id,B.online,A.name
from A inner join B on A.id = B.id
where B.online > 0