6.多表联合查询，去除重复

 

去除重复数据：

语法规则：在select 后加上distinct，就会去除重复。

select distinct book.author,book.title,borrow.BID,student.stuName,student.major from book 
inner join borrow on book.BID=borrow.BID 
inner join student on student.stuID=borrow.stuID order by BID Desc