自身连接（续) SELECT a1.name man,a2.name woman FROM athlete a1,athlete a2 WHERE a1.sex='男'ANDa2.sex='女1 AND a1.group=a2.group An Introduction to Database System An Introduction to Database System 自身连接（续） SELECT a1.name man, a2.name woman FROM athlete a1, athlete a2 WHERE a1.sex='男' AND a2.sex='女' AND a1.group=a2.group