So fügen Sie eine Schleife zu einem SQL SELECT

Question

Ich bin neueren SQL und ich habe mit Refactoring dieses Bit des Codes beauftragt. Wenn ich mir das anschaue, will ich mich übergeben.

Ich versuche, diese Sproc so zu ändern, dass sie eine beliebige Anzahl von Spalten statt einer festen Zahl zurückgeben kann. So sieht es jetzt aus.

ALTER PROCEDURE [frsuser].[usp_report_UnitFeatureHeaders] 
AS 
BEGIN 
CREATE TABLE #features (SortOrder INT IDENTITY(1,1) 
          ,label NVARCHAR(20) ) 
INSERT INTO #features (label) 
    SELECT label FROM UnitAttributeDefinition order by tab_sort_order 

SELECT 'UnitID'             AS UnitID 
     ,'UnitName'             AS UnitName 
     ,'UnitAddress'            AS UnitAddress 
     ,'RateUnitType'            AS RateUnitType 
     ,'TaxDistrict'            AS TaxDistrict 
     ,'ContractType'            AS ContractType 
     ,'InactiveUnit'            AS InactiveUnit 
     ,(SELECT ISNULL(label,'') FROM #features WHERE SortOrder = 1) AS Feature01 
     ,(SELECT ISNULL(label,'') FROM #features WHERE SortOrder = 2) AS Feature02 
     ,(SELECT ISNULL(label,'') FROM #features WHERE SortOrder = 3) AS Feature03 
     ,(SELECT ISNULL(label,'') FROM #features WHERE SortOrder = 4) AS Feature04 
     ....... 
     ,(SELECT ISNULL(label,'') FROM #features WHERE SortOrder = 100) AS Feature100 
    DROP TABLE #features 
END 

Hier ist die Idee von dem, wie ich es aussehen möchte.

ALTER PROCEDURE [frsuser].[usp_report_UnitFeatureHeaders] 
@numberOfFeatures Int = 100 
AS 
BEGIN 
CREATE TABLE #features (SortOrder INT IDENTITY(1,1) 
          ,label NVARCHAR(20) ) 
INSERT INTO #features (label) 
    SELECT label FROM UnitAttributeDefinition order by tab_sort_order 

DECLARE @counter INT = 0; 
DECLARE @featureName NVARCHAR (20) = 'Feature'; 


SELECT 'UnitID'             AS UnitID 
     ,'UnitName'             AS UnitName 
     ,'UnitAddress'            AS UnitAddress 
     ,'RateUnitType'            AS RateUnitType 
     ,'TaxDistrict'            AS TaxDistrict 
     ,'ContractType'            AS ContractType 
     ,'InactiveUnit'            AS InactiveUnit 
     (WHILE @counter < @numberOfFeatures 
      BEGIN 
       SET @featureName = 'Feature' + @counter; 
       (SELECT ISNULL(label,'') FROM #features WHERE SortOrder = @counter) 
      END 
     ) AS @featureName 

DROP TABLE #features 

END

Ist eine solche refactor überhaupt möglich? und wenn ja, wie würde es aussehen?

Answer 1

Sie sollten versuchen, eine dynamische SQL-Abfrage zu erstellen, verketten alle Etiketten, die Sie mit einer while-Schleife müssen und dann die Abfrage mit Sp_executesql laufen sollte es so etwas wie dieses:

ALTER PROCEDURE [frsuser].[usp_report_UnitFeatureHeaders] 
@numberOfFeatures Int = 100 
AS 
BEGIN 
CREATE TABLE #features (SortOrder INT IDENTITY(1,1) 
          ,label NVARCHAR(20) ) 
INSERT INTO #features (label) 
    SELECT label FROM UnitAttributeDefinition order by tab_sort_order 

DECLARE @counter INT = 1; 
DECLARE @featureName NVARCHAR (20) = 'Feature'; 


-- 
DECLARE @SQL_QUERY NVARCHAR(MAX) 


SET @SQL_QUERY = 
' 
SELECT ''UnitID''             AS UnitID 
     ,''UnitName''             AS UnitName 
     ,''UnitAddress''            AS UnitAddress 
     ,''RateUnitType''            AS RateUnitType 
     ,''TaxDistrict''            AS TaxDistrict 
     ,''ContractType''            AS ContractType 
     ,''InactiveUnit''            AS InactiveUnit ' 

-- ADD FEATURES TO YOUR QUERY 

WHILE @counter <= @numberOfFeatures 

BEGIN 

    SET @SQL_QUERY = CAST((SELECT ISNULL(label,'') FROM #features WHERE SortOrder = @counter) AS nvarchar(100)) + ' AS Feauture '+ CAST(@counter as varchar(4)) + ' ' 
END 


SET @SQL_QUERY = 'FROM TABLE ....' --END OF THE QUERY STATEMENT 

DROP TABLE #features  

EXEC sp_executesql @statement = @query 

Ich glaube, Sie sollte @ numberoffeautures mit einem Count der Tabelle, die alle Etiketten enthält und nicht als Parameter für die gespeicherte Prozedur