小编dan*_*988的帖子

我有一个特殊的SQL查询,似乎遇到了一个神秘的性能问题.这是查询:

SELECT COUNT(LengthOfTime) AS TotalTime, 
       SUM(LengthOfTime) AS TotalLength, 
       SUM(LengthOfTime) / COUNT(LengthOfTime) AS AverageTime, 
       SUM(Pops) / COUNT(LengthOfTime) AS AveragePop 
  FROM ((SELECT * 
           FROM (SELECT *, ID & YearRec AS ID2 
                   FROM MyFirstTable 
                 UNION ALL 
                 SELECT *, ID & YearRec AS ID2 
                   FROM Table2011) AS TEMP 
          WHERE STARTTIME >= '8/1/2011 00:00:00' 
            AND StartTime <= '8/5/2011 23:59:59' ) AS TEMP2 
  JOIN AppleTable ON TEMP2.Reason = AppleTable.Skills ) 
  JOIN PeopleTable ON TEMP2.Operator = PeopleTable.Operators 
 WHERE AppleTable.[ON] = 1 
   AND PeopleTable.[ON] = 1 
   AND Rec_Type …