select A表.字段1,A表.字段2,B表.字段返回,C表.字段返回 From A表 ,B表,C表 [where A表,B表,C表关联及各自的条件语句]

select A表.字段1,A表.字段2,B表.字段,C表.字段 from A表 [where A表的条件语句]

-- Create table STUDENT
create table STUDENT
(
ID number,
name nvArchar2(10),
sex char(1),
grade char(1),
age number(2)
)
tablespace SDMP
storage
(
inITial 64K
minextents 1
maxextents unlimited
);
-- Add comments to the columns
comment on column STUDENT.name
is '学生姓名';
comment on column STUDENT.sex
is '学生性别';
comment on column STUDENT.grade
is '年级';
comment on column STUDENT.age
is '年龄';

-- Create table SEXCODE
create table SEXCODE
(
DM char(1),
MC nVARchar2(5)
)
tablespace SDMP
storage
(
initial 64K
minextents 1
maxextents unlimited
);
-- Add comments to the columns
comment on column SEXCODE.DM
is '代码';
comment on column SEXCODE.MC
is '名称';

-- Create table GRADECODE
create table GRADECODE
(
DM CHAR(1),
MC NVARCHAR2(5)
)
tablespace SDMP
pctfree 10
initrans 1
maxtrans 255
storage
(
initial 64K
minextents 1
maxextents unlimited
);
-- Add comments to the columns
comment on column GRADECODE.DM
is '代码';
comment on column GRADECODE.MC
is '名称';

--insert into student
insert into student(id,name,sex,grade,age) values(1,'张三','1','2',8);
insert into student(id,name,sex,grade,age) values(2,'李四','0','1',11);
insert into student(id,name,sex,grade,age) values(3,'王五','1','2',9);
insert into student(id,name,sex,grade,age) values(4,'刘二','0','4',8);
insert into student(id,name,sex,grade,age) values(5,'韩六','0','3',6);

--insert into sexcode
insert into sexcode(dm,mc) values('1','男');
insert into sexcode(dm,mc) values('0','女');

--insert into gradecode
insert into gradecode(dm,mc) values('1','一年级');
insert into gradecode(dm,mc) values('2','二年级');
insert into gradecode(dm,mc) values('3','三年级');

select s.id,s.name,sc.mc sex,gc.mc grade,s.age
from student s,sexcode sc,gradecode gc
where sc.dm=s.sex(+) and s.grade=gc.dm(+)

select s.id,s.name,s.age,
(select mc from sexcode where dm=s.sex) sex,
(select mc from gradecode where dm=s.grade) grade
from student s