左连接 *=(左表中的数据全部显示出来,右表中没有相关联的数据显示null)
select Users.*,Department.name as DepartmentName from Users,Department where users.DepartmentID*=Department.ID
右链接 =*
左连接 *=(左表中的数据全部显示出来,右表中没有相关联的数据显示null)
select Users.*,Department.name as DepartmentName from Users,Department where users.DepartmentID*=Department.ID
右链接 =*