Question

我需要获得用户数量。当我在OR子句中添加WHERE条件时，执行查询需要更多时间。如何优化此SQL查询以最小化执行时间？

SELECT SM.ModelId,
   SM.NameID,
   U.UserCount INTO #SM
FROM Mapper AS SM (NOLOCK) CROSS APPLY (
SELECT COUNT(DISTINCT U.UserNumber) AS UserCount
FROM Team T (NOLOCK)
JOIN Equ E (NOLOCK) ON T.Equid = E.Equid
JOIN EquReq ER (NOLOCK) ON E.EquReqid = ER.EquReqid
LEFT JOIN Information I (NOLOCK) ON T.Equid = I.Equid
JOIN USER U (NOLOCK) ON ER.Key = U.Key
WHERE (T.NameID = SM.NameID
   OR I.NameID = SM.NameID)

Answer 1

您可以尝试运行以下内容 -

SELECT SM.ModelId, SM.NameID, U.UserCount
  INTO #SM    
  FROM Mapper AS SM (NOLOCK)
 CROSS APPLY (SELECT COUNT(DISTINCT U.UserNumber) AS UserCount 
                FROM Team T (NOLOCK)
                JOIN Equ E (NOLOCK) 
                  ON T.Equid = E.Equid
                JOIN EquReq ER (NOLOCK) 
                  ON E.EquReqid = ER.EquReqid
                LEFT JOIN Information I (NOLOCK) 
                  ON T.Equid = I.Equid
                JOIN User U (NOLOCK) 
                  ON ER.Key = U.Key
                WHERE T.NameID = SM.NameID
                UNION
                SELECT COUNT(DISTINCT U.UserNumber) AS UserCount 
                FROM Team T (NOLOCK)
                JOIN Equ E (NOLOCK) 
                  ON T.Equid = E.Equid
                JOIN EquReq ER (NOLOCK) 
                  ON E.EquReqid = ER.EquReqid
                LEFT JOIN Information I (NOLOCK) 
                  ON T.Equid = I.Equid
                JOIN User U (NOLOCK) 
                  ON ER.Key = U.Key
                WHERE I.NameID = SM.NameID)

如果这没有帮助，请确保在T.NameID和amp;上都有足够的覆盖索引。 I.NameID以满足查询。

如果您仍有问题，请告诉我您在下表中的索引 -

T队信息我

在SQL Server中使用OR子句左连接

1 个答案: