Sql server 使用SQL server中的联接高效地选择嵌套的依赖关系表和单行中的多列

我有一个父表“Employee”，员工信息存储在三个子表中，每个子表有一个子表。考虑下面的表格：

表：员工（1级）

表：员工电子邮件（二级）

表：电子邮件地址（第3级）

表：员工电话（2级）

表：电话号码（第3级）

现在我需要选择活动员工记录（完整信息），如果该员工有电话号码，则该号码应为空，否则该号码应为空，我也需要相同的电子邮件号码

我的预期产出：

EmpId        Email             Home        Mobile        Fax
____________________________________________________________________
  1          one@gmail.com     NULL        9912345671    9912345676
(...)

这个问题与我先前的问题相似

---

请帮助我如何在一行中提取多个电话号码？

这是一个简单的

案例

样式

透视

，看起来它适合您的需要：

select 
      e.EmpId
    , Email  = max(em.Email)
    , Home   = max(case when ep.Type = 'Home'   then pn.PhoneNumber else null end)
    , Mobile = max(case when ep.Type = 'Mobile' then pn.PhoneNumber else null end)
    , Fax    = max(case when ep.Type = 'Fax'    then pn.PhoneNumber else null end)
  from Employee as e
    left join EmployeeEmail as ee on  e.EmpId   = ee.EmpId
    left join EmailAddress  as ea on ee.EmailId = ea.EmailId
    left join EmployeePhone as ep on  e.EmpId   = ep.EmpId
    left join PhoneNumber   as pn on ep.PhoneId = pn.PhoneId
  where e.IsActive = 1
  group by e.EmpId

---

这是一个简单的

案例

样式

pivot

，看起来很适合您的需要：

select 
      e.EmpId
    , Email  = max(em.Email)
    , Home   = max(case when ep.Type = 'Home'   then pn.PhoneNumber else null end)
    , Mobile = max(case when ep.Type = 'Mobile' then pn.PhoneNumber else null end)
    , Fax    = max(case when ep.Type = 'Fax'    then pn.PhoneNumber else null end)
  from Employee as e
    left join EmployeeEmail as ee on  e.EmpId   = ee.EmpId
    left join EmailAddress  as ea on ee.EmailId = ea.EmailId
    left join EmployeePhone as ep on  e.EmpId   = ep.EmpId
    left join PhoneNumber   as pn on ep.PhoneId = pn.PhoneId
  where e.IsActive = 1
  group by e.EmpId

EmpPhoneId    EmpId    PhoneId    Type
____________________________________________
1             1         1         Mobile
2             2         2         Mobile
3             5         4         Fax
4             1         6         Fax
5             2         9         Home

PhoneId    PhoneNumber
_______________________
1          9912345671
2          9912345672
3          9912345673
4          9912345674
5          9912345675
6          9912345676
7          9912345677
8          9912345678
9          9912345679

EmpId        Email             Home        Mobile        Fax
____________________________________________________________________
  1          one@gmail.com     NULL        9912345671    9912345676
(...)

select 
      e.EmpId
    , Email  = max(em.Email)
    , Home   = max(case when ep.Type = 'Home'   then pn.PhoneNumber else null end)
    , Mobile = max(case when ep.Type = 'Mobile' then pn.PhoneNumber else null end)
    , Fax    = max(case when ep.Type = 'Fax'    then pn.PhoneNumber else null end)
  from Employee as e
    left join EmployeeEmail as ee on  e.EmpId   = ee.EmpId
    left join EmailAddress  as ea on ee.EmailId = ea.EmailId
    left join EmployeePhone as ep on  e.EmpId   = ep.EmpId
    left join PhoneNumber   as pn on ep.PhoneId = pn.PhoneId
  where e.IsActive = 1
  group by e.EmpId