表结构如下,竟然可以使用自然连接(列名不同),查询代码
select s.sid,s.sname,s.sbirth,s.sclass,s.saddress,c.department,c.cname,d.dname
from Student s natural join class c natural join department d
where d.dname='法律系';
-------------------------------------------------------------
SQL> desc class
名称
是否为空? 类型
----------------------------------------- -------- ----------------------------
CID
NOT NULL VARCHAR2(10)
DEPARTMENT
VARCHAR2(10)
CNAME
VARCHAR2(16)
SQL> desc department
名称
是否为空? 类型
----------------------------------------- -------- ----------------------------
DID
NOT NULL VARCHAR2(10)
DNAME
VARCHAR2(8)
DOFFICE
VARCHAR2(20)
DTELEPHONE
VARCHAR2(8)
DPRINCIPAL
VARCHAR2(10)
SQL> desc student
名称
是否为空? 类型
----------------------------------------- -------- ----------------------------
SID
NOT NULL VARCHAR2(10)
SNAME
VARCHAR2(8)
SBIRTH
DATE
SCLASS
VARCHAR2(10)
SADDRESS
VARCHAR2(20)
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