雪落窗台

1、等值与非等值连接查询

select Student.*,SC.*

from Student,SC

where Student.Sno=SC.Sno;

2、外连接

select Student.sno,sname,ssex,sage,sdept,cno,grade

from Student LEFT JOIN SC ON (Student.sno = SC.sno);

3、自身连接

select FIRST.cno,SECOND.cpno

from Course FIRST,Course SECOND

where FIRST.Cpno = SECOND.Cno;

4、复合条件连接

select Student.Sno,Sname,Grade

from Student,SC

where Student.Sno = SC.Sno AND

SC.Cno =’1′ AND SC.Grade >80;

select Student.Sno,Sname,Cname,Grade

from Student,SC,Course

where Student.Sno = SC.Sno AND SC.Cno = Course.Cno;

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