'有3个表,其中有两个表都和第三个表关联.而这两个表之间则没有什么关联.请问那么查询语句怎么写啊。就是把3个表都合并起来的语句.

select t1.tstuno,t2.tclassname,t3.departno from tstuno as t1,tclassname as t2,departno as t3 where t1.stuname="???",t2.classno="??",t3.departname="???"