-- 操作日志表 CREATE TABLE JobLog  -- 操作日志表 (      JobLogId] int NOT NULL ,       -- 主键      FunctionId nvarchar(20) NULL , -- 功能Id      OperateTime datetime NULL      -- 操作时间 ) ON PRIMARY GO ALTER TABLE JobLog ADD CONSTRAINT PK_JobLog PRIMARY KEY CLUSTERED(JobLogId) ON PRIMARY GO -- 操作日志表的所有记录 SELECT * FROM JobLog 查询结果： 1    001    2007-11-01 2    001    2007-11-02 3    001    2007-11-03 4    002    2007-11-04 5    002    2007-11-05 6    003    2007-11-06 7    004    2007-11-07 8    004    2007-11-08 9    005    2007-11-09 10  005    2007-11-10 -- 每个功能最后一次操作记录 SELECT * FROM JobLog A WHERE JobLogId in         (SELECT TOP 1 JobLogId FROM JobLog          WHERE A.FunctionId = FunctionId ORDER BY OperateTime DESC         ) 查询结果： 3    001    2007-11-03 5    002    2007-11-05 6    003    2007-11-06 8    004    2007-11-08 10  005    2007-11-10

当有大量数据时，上面的语句执行效率很低，数据量超过10万条时，在我的机器上运行了5分钟还没有完成。可以考虑用以下SQL语句： 1. 得到第一条： SELECT * FROM JobLog a, ( SELECT FunctionId, MIN(OperateTime) AS OperateTime FROM JobLog GROUP BY FunctionId ) b WHERE a.FunctionId = b.FunctionId AND a.OperateTime = b.OperateTime 2. 得到最后一条： SELECT * FROM JobLog a, ( SELECT FunctionId, MAX(OperateTime) AS OperateTime FROM JobLog GROUP BY FunctionId ) b WHERE a.FunctionId = b.FunctionId AND a.OperateTime = b.OperateTime 以上语句在数据量10万条时执行时间近5秒。