SQL 2000
NED 表有一个外键到 SIGN 表 NED.RowID 到 SIGN.RowID
SIGN 表有一个外键到 NED 表 SIGN.SignID 到 NED.SignID
RowID 和 SignID 是集群主键,它们是 GUID (不是我的选择)
WHERE 子句是:
FROM
[SIGN] A
INNER JOIN NED N ON A.SIGNID = N.SIGNID
INNER JOIN Wizard S ON A.WizardID = S.WizardID
INNER JOIN [Level] SL ON N.LevelID = SL.LevelID
LEFT JOIN Driver DSL ON SL.LevelID = DSL.LevelID
AND DSL.fsDeptID = @fsDeptID
INNER JOIN [Character] ET ON S.CharacterID = ET.CharacterID
INNER JOIN Town DS ON A.TownID = DS.TownID
WHERE
(A.DeptID = @DeptID OR
S.DeptID = @DeptID
AND
A.[EndTime] > @StartDateTime AND A.[StartTime] < @EndDateTime
AND
A.NEDStatusID = 2
为什么这个查询的 SIGN 表上有一个 INDEX SCAN?什么会导致对聚集索引进行索引扫描?谢谢