Question

我有以下SQL语句来检索项目名称，项目经理和项目状态：

目前，当我将团队成员分配给项目时，它们会从Member表写入ProjectIterationMember表。我想做的是计算该特定项目的团队成员数量。我需要在这个SQL语句中使用它，因为我在datagridview中显示所有内容。谢谢你的帮助！

表格结构：

Project {ProjectID, CompanyID, ProjectName, StartDate, EndDate, Description}
Iterations {ProjectIterationID, ProjectID, StartDate, EndDate}
Member {MemberID, FirstName, LastName, CompanyRole}
ProjectIterationMember {ProjectIterationMemberID, ProjectIterationID, MemberID}

SELECT DISTINCT(Project.ProjectName), 
   Project.ProjectID, Project.Status,
   Project.CompanyID, Project.StartDate,
   m.MemberID, m.FirstName + ' ' + m.LastName AS  
   ProjectManager 
FROM 
   Project, Member m, ProjectIterationMember, Iterations i 
WHERE 
   m.CompanyRole = 'Project Manager' AND Project.CompanyID = '" + co_id + "' AND  
   m.MemberID = ProjectIterationMember.MemberID AND i.ProjectIterationID = 
   ProjectIterationMember.ProjectIterationID AND i.ProjectID = Project.ProjectID ORDER BY 
   Project.StartDate DESC

Answer 1

试试这个：

SELECT YOUR_SELECT_HERE, count(m.MemberID) as MemberCount
FROM YOUR_FROM_HERE
WHERE YOUR_WHERE_HERE
GROUP BY m.MemberID

Answer 2

基本上有两种方法可以做到这一点。

首先：将分组添加到该语句。根据您的数据，这可能有效，也可能无效。正如我所看到的，您目前正加入ProjectIterationMember，前往Projekt经理。要使用分组，您可以第二次为所有其他成员加入。此外，通过分组，您不需要使用distinct。

SELECT Project.ProjectName, 
   Project.ProjectID, Project.Status,
   Project.CompanyID, Project.StartDate,
   m.MemberID, m.FirstName + ' ' + m.LastName AS  
   ProjectManager,
   Count(allMembers.MemberID) AS MemberCount
FROM 
   Project, Member m, ProjectIterationMember, Iterations i, ProjectIterationMember allMembers
WHERE 
   m.CompanyRole = 'Project Manager' AND Project.CompanyID = '" + co_id + "' AND  
   m.MemberID = ProjectIterationMember.MemberID AND i.ProjectIterationID = 
   ProjectIterationMember.ProjectIterationID AND i.ProjectID = Project.ProjectID AND i.ProjectIterationID = 
   allMembers.ProjectIterationID
   GROUP BY Project.ProjectName, 
   Project.ProjectID, Project.Status,
   Project.CompanyID, Project.StartDate,
   m.MemberID, m.FirstName, m.LastName
   ORDER BY 
   Project.StartDate DESC

第二种方法是内部选择。例如，如果您的数据结构不支持此选择中的分组，则需要这样做。您还可以将内部选择导出到用户定义的函数，并在其他地方重复使用。

SELECT DISTINCT(Project.ProjectName), 
   Project.ProjectID, Project.Status,
   Project.CompanyID, Project.StartDate,
   m.MemberID, m.FirstName + ' ' + m.LastName AS  
   ProjectManager,
   (SELECT COUNT(MemberID) FROM ProjectIterationMember WHERE ProjectIterationID = i.ProjectIterationID) AS MemberCount
FROM 
   Project, Member m, ProjectIterationMember, Iterations i 
WHERE 
   m.CompanyRole = 'Project Manager' AND Project.CompanyID = '" + co_id + "' AND  
   m.MemberID = ProjectIterationMember.MemberID AND i.ProjectIterationID = 
   ProjectIterationMember.ProjectIterationID AND i.ProjectID = Project.ProjectID ORDER BY 
   Project.StartDate DESC

计算项目成员数量

2 个答案: