Question

考虑一个包含2列的Employee表

INT数据类型

的ID

NAME是VARCHAR数据类型。

考虑第二个Employee_PHONE表，其中包含2列

INT数据类型

的ID

PHONE，其为VARCHAR数据类型。两者都设置为NOT NULL。

EMPLOYEE_PHONE的ID是引用EMPLOYEE表主键的外键

员工可能没有任何电话或可能有多部电话。什么是SQL查询来显示没有电话的所有员工的姓名？

Answer 1

这可以直接从“英语转换为SQL”

select e.*
from employee e ---<<< get me all employees 
where not exists ---<<< that do not have a phone
          (select *  
           from employee_phone ep
           where ep.employee_id = e.id
             and ep.phone <> ''); -- in case you allow empty strings in that column

Answer 2

这是两个选择查询。

    SELECT * FROM Employee a WHERE a.ID NOT IN (SELECT b.ID FROM Employee_PHONE)

    SELECT * FROM Employee a 
    LEFT JOIN Employee_PHONE b ON a.ID = b.ID WHERE ISNULL(b.PHONE,'') = ''

Answer 3

select E.Name 
from Employee E left Join Employee_PHONE EP
     on E.ID = EP.ID
where EP.EMPLOYEE_PHONE is null or EP.EMPLOYEE_PHONE = ''

Answer 4

试试这个：

select E.Name 
from Employee E left Join Employee_PHONE EP
     on E.ID = EP.ID
where EP.EMPLOYEE_PHONE is null

SQL查询显示没有电话的所有员工的姓名？

4 个答案: