问题
I have this database:
And I need to get the following data for each Client:
- Client Name
- Contract Name(s)
- Project(s)
- Employees who logged hours to a project from the first day of the current month until the last day of the current month
- Total number of hours logged for each employee during the month
- Employee rate
- Total Charges per employee (i.e. employee rate x employee hours worked)
- Billing contact(s) [name, address] for each contract
I have the following query so far, but I need to implement a MSSQL version of MySQL's GROUP_CONCAT( )
SELECT
Cl.LegalName AS ClientNames,
Cr.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 )
WHERE WH_Month = 4
AND WH_Year = 2013
When I started following this example, I got to here and stopped because I realized that I couldn't reference table aliases (Cr) from other subqueries (ProjectNames).
SELECT
Cl.LegalName AS ClientNames,
(
SELECT ContractDesc + ', '
FROM Contracts Cr
WHERE Cl.ClientID = Cr.ClientID
FOR XML PATH('')
) ContractNames,
(
SELECT ProjectName + ', '
FROM Projects P
WHERE Cr.ContractID = P.ContractID
FOR XML PATH('')
) ProjectNames
FROM Clients Cl
How exactly do I go about doing this?
回答1:
Try CROSS APPLY to do yhis:
For Example:
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
回答2:
do like this
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)
回答3:
STRING_AGG is almost equivalent to GROUP_CONCAT in MySQL. Refer the official document from Microsoft here
Note that STRING_AGG doesn't allow Text type, so you need to convert to NVARCHAR if you will concatenate on a Text field.
Example:
STRING_AGG(CONVERT(NVARCHAR(2000), your_text_field_name), ',')
来源：https://stackoverflow.com/questions/19110850/sql-server-equivalent-to-group-concat