相当于组_CONCAT（）的SQL Server

我有这个数据库：

我需要为每个客户机获取以下数据：

• 客户名称
• 合约名称
• 项目
• 从当月第一天到当月最后一天为项目记录小时数的员工
• 当月每位员工记录的总小时数
• 员工工资
• 每位员工的总费用（即员工费率x员工工作小时数）
• 每份合同的账单联系人[姓名、地址]

到目前为止，我有以下查询，但我需要实现MySQL的GROUP_CONCAT（）的MSSQL版本

当我开始下面的示例时，我来到这里并停止了，因为我意识到我无法从其他子查询（projectname）引用表别名（Cr）

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我该怎么做呢？

试着交叉应用来实现这一点：

例如：

SELECT Cl.LegalName AS ClientNames,
B.ContractDesc AS ContractNames,
P.ProjectName AS ProjectNames,
( E.FirstName + ' ' + E.LastName ) AS EmployeeNames,
SUM( WH.HoursWorked ) AS TotalHours, 
( SUM( WH.HoursWorked ) * BR.Rate ) AS TotalCharges, 
( Ca.FirstName + Ca.LastName + ', ' + Ca.AddrLine1 ) AS BillingContacts

FROM Clients Cl
JOIN Contracts Cr ON( Cl.ClientID = Cr.ClientID )
JOIN Projects P ON( Cr.ContractID = P.ContractID )
JOIN EmployeesProjects EP ON( P.ProjectID = EP.ProjectID )
JOIN Employees E ON( EP.EmpID = E.EmpID )
JOIN WorkHours WH ON( E.EmpID = WH.EmpID )
JOIN BillingRates BR ON( E.TitleID = BR.TitleID ) AND ( E.Level = BR.Level )
JOIN ContractsContacts CC ON( Cr.ContractID = CC.ContractID )
JOIN Contacts Ca ON( CC.ContactID = Ca.ContactID ) 
CROSS APPLY (
    SELECT Cr1.ContractDesc + ', '
    FROM Contracts Cr1
    WHERE Cl.ClientID = Cr1.ClientID 
    FOR XML PATH('')
) B (ContractDesc)
WHERE WH_Month = 4 AND WH_Year = 2013

你喜欢这样吗

   SELECT Cl.LegalName AS ClientNames,
   ContractNames
   FROM Clients Cl
    cross apply 
   (SELECT Cr1.ContractDesc + ', '
    FROM Contracts Cr1
      WHERE Cl.ClientID = Cr1.ClientID  For XML PATH(''))a1 (ContractNames)

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STRING_AGG几乎等同于MySQL中的GROUP_CONCAT。请参阅Microsoft的官方文档

请注意，STRING_AGG不允许使用文本类型，因此如果要在文本字段上串联，则需要转换为NVARCHAR

例如：

SELECT Cl.LegalName AS ClientNames,
B.ContractDesc AS ContractNames,
P.ProjectName AS ProjectNames,
( E.FirstName + ' ' + E.LastName ) AS EmployeeNames,
SUM( WH.HoursWorked ) AS TotalHours, 
( SUM( WH.HoursWorked ) * BR.Rate ) AS TotalCharges, 
( Ca.FirstName + Ca.LastName + ', ' + Ca.AddrLine1 ) AS BillingContacts

FROM Clients Cl
JOIN Contracts Cr ON( Cl.ClientID = Cr.ClientID )
JOIN Projects P ON( Cr.ContractID = P.ContractID )
JOIN EmployeesProjects EP ON( P.ProjectID = EP.ProjectID )
JOIN Employees E ON( EP.EmpID = E.EmpID )
JOIN WorkHours WH ON( E.EmpID = WH.EmpID )
JOIN BillingRates BR ON( E.TitleID = BR.TitleID ) AND ( E.Level = BR.Level )
JOIN ContractsContacts CC ON( Cr.ContractID = CC.ContractID )
JOIN Contacts Ca ON( CC.ContactID = Ca.ContactID ) 
CROSS APPLY (
    SELECT Cr1.ContractDesc + ', '
    FROM Contracts Cr1
    WHERE Cl.ClientID = Cr1.ClientID 
    FOR XML PATH('')
) B (ContractDesc)
WHERE WH_Month = 4 AND WH_Year = 2013

STRING_AGG(CONVERT(NVARCHAR(2000), your_text_field_name), ',')

STRING_AGG(CONVERT(NVARCHAR(2000), your_text_field_name), ',')