经典SQL语句大全：三、技巧
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 INT
USE 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)
AS
DECLARE @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 name
OPEN?? 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,@OldOwner
FETCH NEXT FROM curObject INTO @Name, @Owner
END
close 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???? score
??? Zhangshan?? 80
??? Lishi ??????59
??? Wangwu ?????50
??? Songquan??? 69
while((select min(score) from tb_table)<60)
begin
update tb_table set score =score*1.01
where score<60
if? (select min(score) from tb_table)>60
? break
?else
??? continue
end
