select 用法 select * from test (显示所以字段)
select count(*) from test (统计test表中的记录)
select id, name from test(显示部分字段)
select id 学号, name 姓名 from test (取别名)
select * from test where id='007'(显示直到信息)
select * from test where name in=('007','008') (in 用法)
select a.id1,a.name2 from test1 a where not exists (select * from test2 b where b.name2=a.name2) (exists用法)
select distinct name from test (名字不重复)
select * from test order by id desc(按id升序)
select * from test order by id asc (默认)
select * from test order by 2 desc (2 表示第2列)
select * from TBL_TEST start with id=1 connect by prior id = pid (树表查询)
select * from (select * from test order by num asc ) where rownum <3 (显示表中前三条 )
select id,name from test group by id,name (按id,name分组)
select id,name from test group by 1,2 (按id,name分组)
select num,name from test group by num,name having count(*)>1
select id table a,（select id,name count(*) from table group by id,name having count(1)>1） b where b.id=b.id and a.name=b.rg group by id,rg (显示重复记录)
select t1.id id,ti.name name,t2.oder oder1,t3.oder oder2 from test1 t1,test2 t2,test3 t3 where t1.name（+）=t2.name t1.name（+）=t3.name (左右关联)