语句的优化。

--版本是SQL2000--数据量都不大，几万条，但是执行非常慢，要几分钟。。--怎么优化呢UPDATE T_BASE_PARTSALF SET CURRSALF = T1.SAFENUM,                        UPDATETIME=ISNULL(CONVERT(DATETIME,T1.UPDATETIME),GETDATE()),                        UPDATEMAN='SYSMAN'              FROM (SELECT IOSF.SAFENUM,IOSF.UPDATETIME,PART.PARTID,FACT.FACTID FROM T_IO_SAFESTORAGE IOSFLEFT JOIN T_BASE_PART PART ON IOSF.PARTCODEU8=PART.PARTCODELEFT JOIN T_BASE_FACT FACT ON IOSF.FACTCODE=FACT.FACTCODEWHERE ISACTIVE=1) AS T1                        WHERE T_BASE_PARTSALF.PARTID = T1.PARTID AND T_BASE_PARTSALF.FACTID=T1.FACTID 

;WITH TAS(SELECT IOSF.SAFENUM,IOSF.UPDATETIME,PART.PARTID,FACT.FACTID FROM T_IO_SAFESTORAGE IOSFLEFT JOIN T_BASE_PART PART ON IOSF.PARTCODEU8=PART.PARTCODELEFT JOIN T_BASE_FACT FACT ON IOSF.FACTCODE=FACT.FACTCODEWHERE ISACTIVE=1)UPDATE T_BASE_PARTSALF SET CURRSALF = T.SAFENUM,                        UPDATETIME=ISNULL(CONVERT(DATETIME,T1.UPDATETIME),GETDATE()),                        UPDATEMAN='SYSMAN'              FROM T WHERE T_BASE_PARTSALF.PARTID = T1.PARTID AND T_BASE_PARTSALF.FACTID=T1.FACTID这样试试，还有where后面的字段加索引