左外部聯接查詢非常慢-SQL Server

Question

SQL Server查詢的巨大問題！

因此，以下查詢在查詢中利用了JOIN命令，但是運行時間不少於15-20分鍾！ 不知道如何更好地優化此代碼:(

有關如何解決此問題的任何想法？

SELECT dbo.DB_Timetrack.[JOB #], dbo.DB_Timetrack.[Last Name], dbo.DB_Timetrack.[First Name], dbo.DB_Timetrack.HOURS, dbo.DB_Timetrack.BEGDATE, dbo.DB_Timetrack.LOCATNID, 
                         dbo.DB_Timetrack.DESCR, dbo.DB_Timetrack.CODE, dbo.DB_Timetrack.TYPE, 
                         CASE WHEN dbo.DB_Job_status_open_and_closed.WS_Job_Number != '' THEN dbo.DB_Timetrack.Hours ELSE 0 END AS HoursWon, dbo.DB_Timetrack.NUMBERONLY, 
                         dbo.DB_Job_status_open_and_closed.WS_Job_Number_Only, dbo.DB_Job_status_open_and_closed.CREATDDT, DATEDIFF(Day, dbo.DB_Timetrack.BEGDATE, 
                         dbo.DB_Job_status_open_and_closed.CREATDDT) AS Date_Difference, DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID.new_GPSalespersonName, 
                         CASE WHEN DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID.new_GPSalesRepCode <> '' THEN DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID.new_GPSalesRepCode ELSE dbo.DB_Job_status_open_and_closed.Salesperson
                          COLLATE Latin1_General_CI_AI END AS SalespersonID

FROM            dbo.DB_Timetrack LEFT OUTER JOIN
                         DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID ON dbo.DB_Timetrack.NUMBERONLY COLLATE Latin1_General_CI_AI = DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID.Job_Num_Only LEFT OUTER JOIN
                         dbo.DB_Job_status_open_and_closed ON dbo.DB_Timetrack.NUMBERONLY = dbo.DB_Job_status_open_and_closed.WS_Job_Number_Only

WHERE        (dbo.DB_Timetrack.HOURS > 0) AND (dbo.DB_Timetrack.DESCR <> '') AND (dbo.DB_Timetrack.BEGDATE > CONVERT(DATETIME, '2013-01-01 00:00:00', 102))

任何建議將不勝感激！

Answer 1

這基本上是您的查詢：

SELECT . . .
FROM dbo.DB_Timetrack LEFT OUTER JOIN
     DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID
     ON dbo.DB_Timetrack.NUMBERONLY COLLATE Latin1_General_CI_AI = DBCRM_MSCRM.dbo.DB_Opportunity_SalespersonID.Job_Num_Only LEFT OUTER JOIN
     dbo.DB_Job_status_open_and_closed
     ON dbo.DB_Timetrack.NUMBERONLY = dbo.DB_Job_status_open_and_closed.WS_Job_Number_Only
WHERE (dbo.DB_Timetrack.HOURS > 0) AND
      (dbo.DB_Timetrack.DESCR <> '') AND
      (dbo.DB_Timetrack.BEGDATE > CONVERT(DATETIME, '2013-01-01 00:00:00', 102))

1.）首先，排序規則語句可能會殺死對索引的任何使用。

2.）您需要確保在DB_Job_status_open_and_closed(WS_Job_Number_Only)和DB_Opportunity_SalespersonID(Job_Num_Only)上具有索引。

3.）您可能還會在DB_Timetrack(BEGDATE, HOURS, DESCR, NumberOnly)上找到一個索引DB_Timetrack(BEGDATE, HOURS, DESCR, NumberOnly) ，這將有所幫助（如果您確實在使用SQL Server，則最后三列可以include ）。