create table si ( t_id int, s_id int ) ²éѯ³öËùÓÐÀÏʦ´ú¿ÎµÄÃû×Ö£¬ºÍÊýÁ¿£¬Ìõ¼þÊÇÀÏʦµÄÄêÁä´óÓÚ30£¬Ñ§ÉúµÄÄêÁäÊÇ´óÓÚ12 òÊÓÌõ¼þ²»¹»· create table si ( t_id int, s_id int ) Õâ¸ö±í´ú±íʲô¾ßÌåÒâ˼£¿
ÕâÊÇteacherºÍstudentµÄÍâ¼ü±í select t.t_name from si join teacher t on si.t_id = t.t_id join student s on si.s_id = s.s_id where t.t_age > 30 and s.s_age > 12 Ìõ¼þ²»¹»°É£¿Òª²é³ö´ú¿ÎµÄÃû×ÖºÍÊýÁ¿£¬Ôõô¿´²»µ½Óйؿγ̵ÄtableÄØ£¿
up£¡ ÕâÊÇÎÒ×Ô¼ºÐ´µÄ insert into students values(1,'aa',22); insert into student values(2,'bb',21); insert into student values(3,'cc',24); insert into student values(4,'dd',26);
insert into teacher values(1,'a1',43); insert into teacher values(2,'b2',51); insert into teacher values(3,'