SQL语句优化-----请大哥大姐们帮忙？
/*GetData:   SQL:*/SELECT   FI.FID,   OI.FValue   AS   FFuncUrl,   ( 'Org: '+OS.FSpace   +   OS.FID   +   OS.FKind)   AS   FOrgUrl,   ( 'Biz: '+FS.FSpace   +   FS.FID+FS.FKind)   AS   FProcUrl,   'Biz: '+FS2.FPath   +   FS2.FID   +   FS2.FKind   AS   FFuncFileName,   FS2.FDisplayName   AS   FFuncDisplayName,   FS2.FParam   AS   FParam,   FS2.FOrder   AS   FFuncOrder   FROM   [dbo].S_OrgSystem   OS,   [dbo].S_OrgIndex   as   OI   LEFT   JOIN   [dbo].S_FileIndex   AS   FI   ON   (FI.FID   IN   ( 'Proc.Entry.FuncRef ',   'Proc.Activity.FuncRef ')   AND   FI.FValue   =   OI.FValue)   LEFT   JOIN   [dbo].S_FileSystem   AS   FS   ON   (FS.FGUID   =   FI.FSysGUID)   AND   (FS.FInvalid   =   0)   LEFT   JOIN   [dbo].S_FileSystem   AS   FS2   ON   ( 'Biz: '+   FS2.FSpace   +   FS2.FID   +   FS2.FKind)   =   OI.FVALUE   AND   (FS2.FInvalid   =   0)   WHERE   OI.FID   =   'FuncAlloc.Run '   AND   OI.FSysGUID   IN   (SELECT   DISTINCT   OSB.FGUID   FROM   [dbo].[S_OrgSystem]   OSA,   [dbo].[S_OrgSystem]   OSB   WHERE   ((OSA.FDept   +   '& '   +   OSA.FPosition   +   '& '   +   OSA.FPerson)   IN   ( 'AJ.02&YW&00019 '))   AND   (((OSA.FSpace   +   OSA.FID   +   OSA.FKind)   =   (OSB.FSpace   +   OSB.FID+OSB.FKind))   OR   (OSA.FSpace   +   OSA.FID   +   OSA.FKind)   LIKE   (OSB.FSpace   +   OSB.FID   +   OSB.FKind   +   '\% '))   UNION   SELECT   FGUID   FROM   [dbo].[S_OrgSystem]   WHERE   FID   IN   ( 'YW ')   AND   FKind   =   '.PTN ')   AND   OI.FSysGUID   =   OS.FGUID

这条SQL语句执行太慢了，每次都要七八秒，请问如何优化？

------解决方案--------------------
这么多left join 这么多in ,这么多拼串,还有like ,distinct

我觉得难优化..

------解决方案--------------------
汗
------解决方案--------------------
where相当于inner jion，用where替换left jion查询结果会不一样