mysql三表联合查询

-- SELECT d.userId, d.userPhoNum, a.orderId, a.productType, b.courseId, b.courseName, c.payJe
-- FROM bskgk.order_info_detail a 
-- JOIN bskgk.course_info b ON a.productId = b.courseId 
-- JOIN bskgk.order_info c ON c.orderId = a.orderId 
-- JOIN bskgk.user_info d ON d.userId = c.userId
-- WHERE a.payJe > 0;     ＃as可以省略


语法   －－－－>   >    >FROM (表1 INNER JOIN 表2 ON 表1.字段号=表2.字段号) INNER JOIN 表3 ON 表1.字段号=表3.字段号   

Select A.name,B.name from A inner join B on A.id=B.id和

Select A.name,B.name from A,B where A.id=B.id结果是一样的（内连接的inner关键字可省略）；