http://stackoverflow.com/questions/4715677/difference-between-left-join-and-right-join-in-sql-server
http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins
http://stackoverflow.com/questions/4715677/difference-between-left-join-and-right-join-in-sql-server
http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins
转载于:https://www.cnblogs.com/alterhu/p/3362745.html