Question

我发现以下查询在生产环境中运行，这需要很长时间才能执行。有没有办法优化这个逗号分隔值查询？

SELECT 
   EmpID, EmployeeName, DeptID, HomeAddress, EmailId,
   STUFF( (SELECT DISTINCT '@!#' + CT.Country_Name CT
           INNER JOIN Employee_Country EA ON CT.Country_Id = EA.Country_Id 
           WHERE E.EmpID = EA.EmpID AND EA.Active = 1 FOR XML PATH('')), 1, 3, '') as 'Country',
   STUFF( (SELECT DISTINCT '@!#' + CT.CityName CT
           INNER JOIN Employee_City EA ON CT.City_Id = EA.City_Id 
           WHERE E.EmpID = EA.EmpID AND EA.Active = 1 FOR XML PATH('')), 1, 3, '') as 'City',
   STUFF( (SELECT DISTINCT '@!#' + CT.Number CT
           INNER JOIN Employee_PhonNumbers EA ON CT.PNumberId = EA.PNumberId 
           WHERE E.EmpID = EA.EmpID AND EA.Active = 1 FOR XML PATH('')), 1, 3, '') as 'PhoneNumber',
------so on------
FROM Employee E
WHERE Active = 1

Answer 1

尝试此备用

SELECT EmpID,
       EmployeeName,
       DeptID,
       HomeAddress,
       EmailId,
       Country_Name= LEFT(Country_Name, Len(Country_Name) - 1),
       CityName= LEFT(CityName, Len(CityName) - 1),
       Number= LEFT(Number, Len(Number) - 1)
FROM   Employee E
       OUTER APPLY (SELECT DISTINCT '@!#' + CT.Country_Name
                    FROM   country CT
                           INNER JOIN Employee_Country EA
                                   ON CT.Country_Id = EA.Country_Id
                    WHERE  E.EmpID = EA.EmpID
                           AND EA.Active = 1
                    FOR XML PATH('')) Country (Country_Name)
       OUTER APPLY (SELECT DISTINCT '@!#' + CT.CityName
                    FROM   City CT
                           INNER JOIN Employee_City EA
                                   ON CT.City_Id = EA.City_Id
                    WHERE  E.EmpID = EA.EmpID
                           AND EA.Active = 1
                    FOR XML PATH('')) City (CityName)
       OUTER APPLY (SELECT DISTINCT '@!#' + CT.Number
                    FROM   PhonNumbers CT
                           INNER JOIN Employee_PhonNumbers EA
                                   ON CT.PNumberId = EA.PNumberId
                    WHERE  E.EmpID = EA.EmpID
                           AND EA.Active = 1
                    FOR XML PATH('')) PhonNumbers (Number)
GROUP  BY Name,
          EmployeeName,
          DeptID,
          HomeAddress,
          EmailId,
          LEFT(Country_Name, Len(Country_Name) - 1),
          LEFT(CityName, Len(CityName) - 1),
          LEFT(Number, Len(Number) - 1)

如何在sql server

1 个答案: