请教一道sql表达式练习题

[junnyfeng]

employee(employee-name#,street,city)
works(employee-name#,company-name,salary)
company(company-name#,city)
manages(employee-name#,manager-name)

这是员工数据库的表，#表示为key，书写时不必写出

问题：

用sql表达式 找出数据库中所有居住街道和城市都与其经理相同的员工。

[rivery]

select * from employee
where city in(select a.city from company a,works b,manages c
where a.company-name=b.company-name and b.employee-name=c.employee-name)

[junnyfeng]

自己写了个不知对不对

SELECT employee-name
FROM employee
WHERE employee-name not in (select employee-name from manages) and
street in(select street from employee e,manages m where e.employee-name=m.employee-name) and
city in(select city from employee e,manages m where e.employee-name=m.employee-name);

[vivianfdlpw]

select * from employee t
where exists(select 1 from employee
where street=t.street and
city=t.city and
employee-name=(select top 1 manager-name
from manages
where employee-name=t.employee-name
)
)

[junnyfeng]

select 1跟select top 1是什么意思？小弟初学

[junnyfeng]

up

[postfxj]

select 1 from table
意思是table中有多數據，就會有多少個1
select top 1 from table
選前一筆數據