Question

我正在做一个学校项目而且我被困住了。

要求是编写单个查询，从9个不同的表中收集数据并返回结果。

需要客户名称，合同名称，项目名称，4月份记录小时数的员工，员工记录的总小时数，员工费率，项目每位员工的费用以及每份合同的联系人姓名。
（我知道，需要提取大量数据。）

表格是：

 Clients   
-------------------------------
ClientID | CommonName  

 ContractTypes   
--------------------------------------  
ContractTypeID | ContractType   

 Contracts   
---------------------------------------------------------  
ContractID | ClientID (FK) | ContractType (FK)   

 Projects   
---------------------------------------------------  
ProjectID | ProjectName | ContractID (FK)   

 Contacts   
-----------------------------------------  
ContactID | FirstName | LastName  

 ContractContacts   
--------------------------------------------------  
ContractID (PK/FK) | ContactID (PK/FK)   

 Employees   
-----------------------------------  
EmpID | name | titleID | level   

 BillingRates   
----------------------  
titleID | level | rate  

 WorkHours   
----------------------------  
EmpID | HoursWorked

我运行了以下内容，但结果是超过23,000行 - 不是需要的：

select 
   clients.CommonName, projects.ProjectName, employees.FirstName,  
   employees.lastname, sum(workhours.hoursworked) as TotalHours,  
   BillingRates.Rate,contacts.FirstName, contacts.LastName,     
   contacts.AddrLine1, contacts.AddrLine2, contacts.City, 
   contacts.State_Province, contacts.Zip
from 
   employees, BillingRates, Clients, Projects, WorkHours, Contracts, Contacts
group by 
   clients.CommonName, projects.ProjectName, employees.FirstName,  
   employees.lastname, BillingRates.Rate, contacts.FirstName, 
   contacts.LastName, contacts.AddrLine1, contacts.AddrLine2, 
   contacts.City, contacts.State_Province, contacts.Zip

老实说，我不知道如何将所有数据输入一个查询以生成一个报告。

我收到了有关生成查询的帮助，以便返回4月份记录小时数的员工，员工记录的总小时数以及以下项目的每位员工费用：

select 
   employees.EmpID, 
   sum(workhours.hoursworked) as 'TotalHours',
   firstname, lastname, 
   ISNULL(sum(workhours.hoursworked), 0) * ISNULL(min(rate), 0) AS 'TotalRate'
from 
   employees 
inner join 
   workhours on employees.empid = WorkHours.EmpID
left join  
   BillingRates on employees.titleid = billingrates.titleid
                and employees.level = billingrates.level
where 
   WH_Month = 4
group by 
   LastName, firstname, employees.EmpID

我假设此查询将嵌套到外部查询中，但我不知道如何构造它。

是否有人能够协助撰写此查询？

Answer 1

您可以根据需要添加任意数量的联接;

from
    contracts
    inner join contractcontacts on contracts.contractID = contractcontacts.contractID
    inner join contracttypes on contracts.contracttype = contracttypes.contracttype
    inner join contacts on contactcontacts.contactID = contacts.contactID
    inner join clients on contracts.clientID = clients.clientID
    ...

只需添加具有不同关系的所有表格。例如，检查它是否需要保留外连接而不是内连接，这意味着右侧表可能没有任何行，并且您希望这些行显示为NULL而不是抑制整行。

Answer 2

您可以使用内部联接，但我没有看到FK所有表与另一个表连接。从雇员内连接BillingRates ??? 内部联接客户端cls on ??? 内连接在cls.clientid = cs.clientid上收缩cs 内部联接项目ps on，ps.contractid = cs.contractid 内部联接WorkHours ws on e.empid = ws.empid enter code here 内部联接ContractContacts cscs on cs.contractid = cscs.contractid 内部联接联系人c在c.contact_id = cscs.contactid

上

如果您知道答案而不是上面的联接来解决您的问题，您将如何加入员工的计费率和客户？

Answer 3

非常感谢您的帮助。

我能够提出以下问题：

select clients.CommonName, projects.ProjectName, employees.FirstName,  
   employees.lastname, sum(workhours.hoursworked) as TotalHours,  
   BillingRates.Rate,contacts.FirstName, contacts.LastName,     
   contacts.AddrLine1, contacts.AddrLine2, contacts.City, 
   contacts.State_Province, contacts.Zip
   ISNULL(sum(workhours.hoursworked), 0) * ISNULL(min(rate), 0) AS TotalRate  
from Contracts   
    inner join ContractsContacts on contracts.ContractID =         ContractsContacts.contractid  
    inner join contracttypes on contracts.ContractTypeID =         contracttypes.ContractTypeID  
    inner join contacts on ContractsContacts.ContactID = contacts.ContactID
inner join projects on contracts.ContractID = projects.ContractID
inner join Clients on contracts.ClientID = clients.ClientID
inner join WorkHours on WorkHours.ProjectID = projects.ProjectID
inner join Employees on WorkHours.EmpID = Employees.EmpID
left join BillingRates on Employees.TitleID = BillingRates.TitleID and
Employees.Level = BillingRates.Level  
where workhours.WH_Month = 4  
order by Clients.CommonName, Projects.ProjectName, Employees.LastName

但我无法弄清楚如何将4月份每名员工的总工作时数加起来，以及将费率乘以查询的倍数。我使用以下查询来获取该信息，但我不知道如何将其添加到更长的查询中：

select 
   employees.EmpID, 
   sum(workhours.hoursworked) as 'TotalHours',
   firstname, lastname, 
   ISNULL(sum(workhours.hoursworked), 0) * ISNULL(min(rate), 0) AS 'TotalRate'
from 
   employees 
inner join 
   workhours on employees.empid = WorkHours.EmpID
left join  
   BillingRates on employees.titleid = billingrates.titleid
            and employees.level = billingrates.level
where 
   WH_Month = 4
group by 
   LastName, firstname, employees.EmpID

我很感激你的帮助。

从多个表中检索值

3 个答案: