SQL Server：想要在 UNION 上的 ORDER BY 中使用变量

Question

我读到这应该是可能的，但我无法让它发挥作用！我试过两种方式设置字段名称 - 没有骰子。

USE RTIDatastore;
DECLARE @PAYE AS VARCHAR(20) = 'T6901' -- 'F1867' -- 'S860'
DECLARE @Product AS VARCHAR(20) = 'ADPFREEDOMAS2';
DECLARE @TaxYear AS CHAR(2) = '15';     -- NB No EMP data for FPS14s
DECLARE @EndPeriod AS INTEGER = 6;
DECLARE @OrderBy AS CHAR(1) = 'S';
DECLARE @OrderTest AS VARCHAR(10) = 'NINO'; -- 'Name';
-- this gets all the EMP records, and the first associated NI records (if any)
SELECT
   R.[EmployerPAYE]                                                AS PAYE
 , H.[ICR]                                                         AS ICR
 , E.[NINO]                                                        AS NINo
 , E.[Surname] + ', ' + E.[Forename]                               AS Name
 , E.[Surname]                              AS SurName          -- added for testing
 , E.[Forename]                             AS ForeName         -- added for testing
 , EMP.[EmploymentID]                                              AS EmploymentID
 , EMP.[ATT3_19_PayrollID]                                         AS ATT3_19_PayrollID     -- identifies EMP record
 , EMP.[ALC14_TaxCode]                                             AS ALC1_4_TaxCode
 , NI.[Employee_NI]                                                AS NI_PK
 , NI.[Emp2_NILetter]                                              AS EMP2_NILetter
FROM [RTIDatastore].[dbo].[Header] H
 JOIN      [RTIDatastore].[dbo].[Employer]    R   ON H.[HeaderID] = R.[HeaderID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee]    E   ON R.[EmployerID] = E.[EmployerID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employment]  EMP ON E.[EmployeeID] = EMP.[EmployeeID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee_NI] NI  ON EMP.[EmploymentID] = NI.[EmploymentID_FK]
WHERE H.[SenderID] = @Product
 AND H.[MessageType] = 'FPS' + @TaxYear
 AND R.[EmployerPAYE] = @PAYE
 AND (NI.[Employee_NI] LIKE '%_NI_1' OR NI.[Employee_NI] IS NULL)
UNION
-- this gets any additional NI records
SELECT
   R.[EmployerPAYE]                                                AS PAYE
 , H.[ICR]                                                         AS ICR
 , E.[NINO]                                                        AS NINo
 , E.[Surname] + ', ' + E.[Forename]                               AS Name
 , E.[Surname]                              AS SurName
 , E.[Forename]                             AS ForeName
 , EMP.[EmploymentID]                                              AS EmploymentID
 , EMP.[ATT3_19_PayrollID]                                         AS ATT3_19_PayrollID     -- identifies EMP record
 , EMP.[ALC14_TaxCode]                                             AS ALC1_4_TaxCode
 , NI.[Employee_NI]                       AS NI_PK
 , NI.[Emp2_NILetter]                     AS EMP2_NILetter
FROM [RTIDatastore].[dbo].[Header] H
 JOIN      [RTIDatastore].[dbo].[Employer]    R   ON H.[HeaderID] = R.[HeaderID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee]    E   ON R.[EmployerID] = E.[EmployerID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employment]  EMP ON E.[EmployeeID] = EMP.[EmployeeID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee_NI] NI  ON EMP.[EmploymentID] = NI.[EmploymentID_FK]
WHERE H.[SenderID] = @Product
 AND H.[MessageType] = 'FPS' + @TaxYear
 AND R.[EmployerPAYE] = @PAYE
 AND NI.[Employee_NI] NOT LIKE '%_NI_1'
-- generally Surname is safer than NINo or PayrollID, but not always!
--ORDER BY CASE WHEN @OrderBy = 'N' THEN NINo
--              WHEN @OrderBy = 'P' THEN ATT3_19_PayrollID
--              ELSE Surname
--         END
--     , ICR
--     , EmploymentID
--     , NI_PK
ORDER BY @OrderTest -- Name
 --, NINo
 --, ATT3_19_PayrollID
 , ICR
 , EmploymentID
 , NI_PK

上述两个 ORDER 子句都失败了，但这工作正常：

ORDER BY Name
 --, NINo
 --, ATT3_19_PayrollID
 , ICR
 , EmploymentID
 , NI_PK

我需要将代码放入存储过程中，所以我真的不想写3次，因为可能不同的顺序要求...

Answer 1

您也可以使用 Exec 执行 proc 并构建您的 order by 子句，但我认为在一个答案中演示的条件 Order by 更好，除非您想在字符串中指定 order by。

DECLARE @PAYE AS VARCHAR(20) = 'T6901' -- 'F1867' -- 'S860'
DECLARE @Product AS VARCHAR(20) = 'ADPFREEDOMAS2';
DECLARE @TaxYear AS CHAR(2) = '15';     -- NB No EMP data for FPS14s
DECLARE @EndPeriod AS INTEGER = 6;
DECLARE @OrderBy AS CHAR(1) = 'S';
DECLARE @OrderTest AS VARCHAR(10) = 'NINO'; -- 'Name';
-- this gets all the EMP records, and the first associated NI records (if any)

DECLARE @SqlString nvarchar(max)
Select @SqlString = 'SELECT
   R.[EmployerPAYE]                                                AS PAYE
 , H.[ICR]                                                         AS ICR
 , E.[NINO]                                                        AS NINo
 , E.[Surname] + '', '' + E.[Forename]                               AS Name
 , E.[Surname]                              AS SurName          -- added for testing
 , E.[Forename]                             AS ForeName         -- added for testing
 , EMP.[EmploymentID]                                              AS EmploymentID
 , EMP.[ATT3_19_PayrollID]                                         AS ATT3_19_PayrollID     -- identifies EMP record
 , EMP.[ALC14_TaxCode]                                             AS ALC1_4_TaxCode
 , NI.[Employee_NI]                                                AS NI_PK
 , NI.[Emp2_NILetter]                                              AS EMP2_NILetter
FROM [RTIDatastore].[dbo].[Header] H
 JOIN      [RTIDatastore].[dbo].[Employer]    R   ON H.[HeaderID] = R.[HeaderID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee]    E   ON R.[EmployerID] = E.[EmployerID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employment]  EMP ON E.[EmployeeID] = EMP.[EmployeeID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee_NI] NI  ON EMP.[EmploymentID] = NI.[EmploymentID_FK]
WHERE H.[SenderID] = @Product
 AND H.[MessageType] = ''FPS'' + @TaxYear
 AND R.[EmployerPAYE] = @PAYE
 AND (NI.[Employee_NI] LIKE ''%_NI_1'' OR NI.[Employee_NI] IS NULL)
UNION
-- this gets any additional NI records
SELECT
   R.[EmployerPAYE]                                                AS PAYE
 , H.[ICR]                                                         AS ICR
 , E.[NINO]                                                        AS NINo
 , E.[Surname] + '', '' + E.[Forename]                               AS Name
 , E.[Surname]                              AS SurName
 , E.[Forename]                             AS ForeName
 , EMP.[EmploymentID]                                              AS EmploymentID
 , EMP.[ATT3_19_PayrollID]                                         AS ATT3_19_PayrollID     -- identifies EMP record
 , EMP.[ALC14_TaxCode]                                             AS ALC1_4_TaxCode
 , NI.[Employee_NI]                       AS NI_PK
 , NI.[Emp2_NILetter]                     AS EMP2_NILetter
FROM [RTIDatastore].[dbo].[Header] H
 JOIN      [RTIDatastore].[dbo].[Employer]    R   ON H.[HeaderID] = R.[HeaderID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee]    E   ON R.[EmployerID] = E.[EmployerID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employment]  EMP ON E.[EmployeeID] = EMP.[EmployeeID_FK]
 LEFT JOIN [RTIDatastore].[dbo].[Employee_NI] NI  ON EMP.[EmploymentID] = NI.[EmploymentID_FK]
WHERE H.[SenderID] = @Product
 AND H.[MessageType] = ''FPS'' + @TaxYear
 AND R.[EmployerPAYE] = @PAYE
 AND NI.[Employee_NI] NOT LIKE ''%_NI_1''
ORDER BY ' + @OrderTest + '
 , ICR
 , EmploymentID
 , NI_PK'

 exec sp_executesql @stmt = @sqlString, @params = N'@Product AS VARCHAR(20), @TaxYear AS CHAR(2), @EndPeriod AS INTEGER, @PAYE AS VARCHAR(20)', @Product = @Product, @TaxYear = @TaxYear, @EndPeriod = @EndPeriod, @PAYE = @PAYE

Answer 2

也许您可以将查询包装到新的 SELECT 中，并将 order by 应用于整体结果。像这样：

SELECT * FROM (

  -- Your original unioned query without order by here --

) T

ORDER BY ...

Answer 3

不能直接使用参数进行排序.. 使用类似的东西

SELECT * FROM TableName WHERE [Condition] ORDER BY 
CASE @OrderByColumn
    WHEN Condition1 THEN Value1
    WHEN Condition2 THEN Value2