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下面是小编精心整理的计算机等考三级数据库技术SQL语句辅导技巧篇，仅供参考，大家一起来看看吧。
为大家更好的备考全国计算机等级考试，现学习啦小编专门准备了计算机三级《数据库技术》考前复习重点：数据库SQL语句辅导技巧篇，希望可以帮到你!
计算机等考三级数据库技术SQL语句辅导：技巧篇
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 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
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