枕边小记忆：MySQL -- 技巧提升篇** 1 、1=1，1=2的使用，在SQL语句组合时用的较多**“where 1= 1”是表示选择全部 “where 1=2”全部不选， 如： if @strWhere !='' begin set @strSQL = 'select count() as Total from [' + @tblName + '] where ' + @strWhere end else begin set @strSQL = 'select count() as Total from [' + @tblName + ']' end我们可以直接写成错误！未找到目录项。 ** set @strSQL = 'select count(*) as Total from [' + @tblName + '] where 1=1 安定 '+ @strWhere 2、收缩数据库 **--重建索引 DBCC REINDEX DBCC INDEXDEFRAG --收缩数据和日志 DBCC SHRINKDB DBCC SHRINKFILE**3 、压缩数据库**dbcc shrinkdatabase(dbname)**4 、转移数据库给新用户以已存在用户权限**exec sp_change_users_login 'update_one','newname','oldname' go**5 、检查备份集**RESTORE VERIFYONLY from disk='E:\dvbbs.bak'**6 、修复数据库**ALTER DATABASE [dvbbs] SET SINGLE_USER GO DBCC CHECKDB('dvbbs',repair_allow_data_loss) WITH TABLOCK GO ALTER DATABASE [dvbbs] SET MULTI_USER GO**7 、日志清除**SET NOCOUNT ON DECLARE @LogicalFileName sysname, @MaxMinutes INT, @NewSize INTUSE tablename -- 要操作的数据库名 SELECT @LogicalFileName = 'tablename_log', -- 日志文件名 @MaxMinutes = 10, -- Limit on time allowed to wrap log. @NewSize = 1 -- 你想设定的日志文件的大小(M)Setup / initialize DECLARE @OriginalSize int SELECT @OriginalSize = size FROM sysfiles WHERE name = @LogicalFileName SELECT 'Original Size of ' + db_name() + ' LOG is ' + CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' + CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB' FROM sysfiles WHERE name = @LogicalFileName CREATE TABLE DummyTrans (DummyColumn char (8000) not null)DECLARE @Counter INT, @StartTime DATETIME, @TruncLog VARCHAR(255) SELECT @StartTime = GETDATE(), @TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY'DBCC SHRINKFILE (@LogicalFileName, @NewSize) EXEC (@TruncLog) -- Wrap the log if necessary. WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired AND @OriginalSize = (SELECT size FROM sysfiles WHERE name = @LogicalFileName) AND (@OriginalSize * 8 /1024) > @NewSize BEGIN -- Outer loop. SELECT @Counter = 0 WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000)) BEGIN -- update INSERT DummyTrans VALUES ('Fill Log') DELETE DummyTrans SELECT @Counter = @Counter + 1 END EXEC (@TruncLog) END SELECT 'Final Size of ' + db_name() + ' LOG is ' + CONVERT(VARCHAR(30),size) + ' 8K pages or ' + CONVERT(VARCHAR(30),(size*8/1024)) + 'MB' FROM sysfiles WHERE name = @LogicalFileName DROP TABLE DummyTrans SET NOCOUNT OFF**8 、说明：更改某个表**exec sp_changeobjectowner 'tablename','dbo'9 、存储更改全部表 ****CREATE PROCEDURE dbo.User_ChangeObjectOwnerBatch @OldOwner as NVARCHAR(128), @NewOwner as NVARCHAR(128) ASDECLARE @Name as NVARCHAR(128) DECLARE @Owner as NVARCHAR(128) DECLARE @OwnerName as NVARCHAR(128)DECLARE curObject CURSOR FOR select 'Name' = name, 'Owner' = user_name(uid) from sysobjects where user_name(uid)=@OldOwner order by nameOPEN curObject FETCH NEXT FROM curObject INTO @Name, @Owner WHILE(@@FETCH_STATUS=0) BEGIN if @Owner=@OldOwner begin set @OwnerName = @OldOwner + '.' + rtrim(@Name) exec sp_changeobjectowner @OwnerName, @NewOwner end -- select @name,@NewOwner,@OldOwnerFETCH NEXT FROM curObject INTO @Name, @Owner ENDclose curObject deallocate curObject GO**10 、SQL SERVER中直接循环写入数据**declare @i int set @i=1 while @i<30 begin insert into test (userid) values(@i) set @i=@i+1 end 案例 **：** 有如下表，要求就裱中所有沒有及格的成績，在每次增長 0.1的基礎上，使他們剛好及格:Name scoreZhangshan 80Lishi 59Wangwu 50Songquan 69while((select min (score) from tb_table) < 60 )beginupdate tb_table set score = score* 1.01 ****where score < 60 ****if (select min (score) from tb_table) > 60 ****breakelsecontinueend