sql问题请高手解答一下

Question

有两张表
Employee
EmployID  EmployName DepartmentID
001        A         001
002        B         002
003        C         003Department
DepartmentID  DepartmentName  Address
001            D1              Shanghai
002            D2              Shanghai
003            D3              Beijing比较以下两条sql语句有什么不同，为什么？
select e.employName,d.departmentName from Employee e left join Department d on e.DepartmentID=d.DepartmentID where address='Shanghai'select e.employName,d.departmentName from Employee e left join Department d on e.DepartmentID=d.DepartmentID and d.Address='Shanghai'

Answer 1

select e.employName,d.departmentName from Employee e left join Department d on e.DepartmentID=d.DepartmentID where address='Shanghai'
左连之后再进行Where条件判断
select e.employName,d.departmentName from Employee e left join Department d on e.DepartmentID=d.DepartmentID and d.Address='Shanghai'
左连关系是e.DepartmentID=d.DepartmentID and d.Address='Shanghai'这两个得出来的的结果是不一样的