from name as id为啥报错

select T.name, S.course_id
from instructor  as T, teaches as S
where T.ID= S.ID;

报错

ORA-00933: SQL 命令未正确结束
00933. 00000 -  "SQL command not properly ended"

原因是：
oracle 目前不支持此操作，应改为

select T.name, S.course_id
from instructor  T, teaches  S
where T.ID= S.ID;

即表名和别名中间打个空格即可。