概念:多表连接查询是从多个表中获取数据.
语法:
table_reference
[INNER] JOIN {LEFT|RIGHT}[OUTER]JOIN
table_reference
ON condition_expr
示例:通过查看图书信息表和图书类别表来获取图书编号、图书名称、图书类别
select book_id,book_name,category
from bookinfo
inner join bookcategory
on bookinfo.book_category_id = bookcategory.category_id;
