<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[数据的阶梯]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/Trance</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; Trance]]></copyright><item><title><![CDATA[sql server 分区表数据迁移时巧用switch]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5723698</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5723698</guid><author>Trance</author><pubDate>Fri, 09 Jul 2010 16:13:00 +0800</pubDate><description><![CDATA[-- create partition function 
CREATE PARTITION FUNCTION partRange1 (INT) 
AS RANGE LEFT FOR VALUES (10, 20, 30) ; 
GO 
-- create partition scheme 
CREATE PARTITION SCHEME partScheme1 
AS PARTITION partRange1 
ALL TO ([PRIMARY]) ; 
GO 
-- create ta]]></description><category></category></item><item><title><![CDATA[利用触发器生成自增列]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5534885</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5534885</guid><author>Trance</author><pubDate>Tue, 27 Apr 2010 16:09:00 +0800</pubDate><description><![CDATA[利用触发器生成自增列--环境 create table test_5 ( id int primary key not null, value int ) --保存最大序列值的表 create table Sequence ( rn int ) insert Sequence select 0 go create trigger tr_test_5 on test_5 Instead of ins]]></description><category></category></item><item><title><![CDATA[索引视图在特殊约束中的应用]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5534826</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5534826</guid><author>Trance</author><pubDate>Tue, 27 Apr 2010 16:02:00 +0800</pubDate><description><![CDATA[索引视图在特殊约束中的应用--环境：  IF OBJECT_ID(dbo.V1) IS NOT NULL DROP VIEW dbo.V1; GO IF OBJECT_ID(dbo.T1) IS NOT NULL DROP TABLE dbo.T1; GO CREATE TABLE dbo.T1 ( keycol INT NULL, datacol VARCHAR(10) NOT NULL]]></description><category></category></item><item><title><![CDATA[索引视图在特殊约束中的应用]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5534784</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5534784</guid><author>Trance</author><pubDate>Tue, 27 Apr 2010 15:55:00 +0800</pubDate><description><![CDATA[索引视图在特殊约束中的应用--环境：  IF OBJECT_ID('dbo.V1') IS NOT NULL DROP VIEW dbo.V1; GO IF OBJECT_ID('dbo.T1') IS NOT NULL DROP TABLE dbo.T1; GO CREATE TABLE dbo.T1 ( keycol INT NULL, datacol VARCHAR(10) NOT NULL ); GO 我想在keycol这个字段上建立唯一约束(注意这里的字段是可以为NULL的),这样就意味着可以插入]]></description><category></category></item><item><title><![CDATA[SQL Server的一些系统变量]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5534382</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5534382</guid><author>Trance</author><pubDate>Tue, 27 Apr 2010 15:09:00 +0800</pubDate><description><![CDATA[SQL Server的一些系统变量sp_configure min server memory --服务器最小内存gosp_configure max server memory --服务器最大内存gosp_configure index create memory--创建索引占用的内存go--sp_configure min  memory per query--每次查询占用的]]></description><category></category></item><item><title><![CDATA[SQL server Exec中变量的传递]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/5534294</link><guid>https://blog.youkuaiyun.com/Trance/article/details/5534294</guid><author>Trance</author><pubDate>Tue, 27 Apr 2010 14:56:00 +0800</pubDate><description><![CDATA[SQL server Exec中变量的传递declare @sql2 nvarchar(500) , @count int set @sql2 = select @COUNT = 1 execute sp_executesql @sql2, N@COUNT int output, @count output]]></description><category></category></item><item><title><![CDATA[DB2中有关日期和时间的函数，及应用]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4748976</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4748976</guid><author>Trance</author><pubDate>Fri, 30 Oct 2009 17:14:00 +0800</pubDate><description><![CDATA[DAYNAME         		返回一个大小写混合的字符串，对于参数的日部分，用星期表示这一天的名称（例如，Friday）。   DAYOFWEEK    				返回参数中的星期几，用范围在 1-7 的整数值表示，其中 1 代表星期日。   DAYOFWEEK_ISO 			返回参数中的星期几，用范围在 1-7 的整数值表示，其中 1 代表星期一。   DAYOFYEAR      			返]]></description><category></category></item><item><title><![CDATA[DB2 XQuery 的使用]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4744289</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4744289</guid><author>Trance</author><pubDate>Thu, 29 Oct 2009 17:40:00 +0800</pubDate><description><![CDATA[下面的一些例子也使用了嵌入SQL的XQuery (使用“db2-fn:sqlquery”函数)例1： xquery db2-fn:xmlcolumn(‘CLIENTS.CONTACT’) CLIENT为表名，CONTACT是表CLIENT中的XML字段。该语句等同SQL语句： SELECT contact FROM clients]]></description><category></category></item><item><title><![CDATA[DB2 SQL/XML使用]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4743675</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4743675</guid><author>Trance</author><pubDate>Thu, 29 Oct 2009 16:05:00 +0800</pubDate><description><![CDATA[函数：XMLPARSE：解析字符或者大对象二进制数据，产生XMLXMLSERIALIZE：将XML值转换为字符或者大对象二进制数据XMLVALIDATE：根据XML schema校验XML值的有效性XMLEXISTS：检测XQuery是否返回结果（如由一个或多个项所组成的序列）XMLQUERY：执行一个XQuery并以一个序列返回结果XMLTABLE：执行一个XQuer]]></description><category></category></item><item><title><![CDATA[XPath的语法]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4742803</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4742803</guid><author>Trance</author><pubDate>Thu, 29 Oct 2009 13:46:00 +0800</pubDate><description><![CDATA[列子：                 John Doe 408 555 1212344   Peter Pan 408 555 9918216   语法： XPathResult/dept/@bldg101/dept/employee/@id901902]]></description><category></category></item><item><title><![CDATA[锁和事务]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4737981</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4737981</guid><author>Trance</author><pubDate>Wed, 28 Oct 2009 13:45:00 +0800</pubDate><description><![CDATA[ 锁类型：共享 (S) 保护资源，以便只能对其进行读取访问。当资源上存在共享 (S) 锁时，其他事务均不能修改数据。排他 (X)指示数据修改，例如插入、更新或删除。确保不能同时对同一资源进行多个更新。更新 (U)防止常见形式的死锁。每次只有一个事务可以获得资源上的 U 锁。如果事务修改资源，]]></description><category></category></item><item><title><![CDATA[[SQL Server]延迟执行]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4737864</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4737864</guid><author>Trance</author><pubDate>Wed, 28 Oct 2009 13:19:00 +0800</pubDate><description><![CDATA[WAITFOR指定触发语句块、存储过程或事务执行的时间、时间间隔或事件。语法WAITFOR { DELAY time | TIME time }参数DELAY指示 Microsoft® SQL Server™ 一直等到指定的时间过去，最长可达 24 小时。time要等待的时间。可以按 datetime 数据可接受的格式指定 time，也可]]></description><category></category></item><item><title><![CDATA[覆盖索引]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4737347</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4737347</guid><author>Trance</author><pubDate>Wed, 28 Oct 2009 11:12:00 +0800</pubDate><description><![CDATA[覆盖索引(covering indexex)：一个索引包含了(或覆盖了)满足查询结果的数据 如：create tableorders(id int identity(1, 1),customer_id int,product_id int,quantity intprimary key (id))gocreate table product(id int identity(]]></description><category></category></item><item><title><![CDATA[SQL Server 四种隔离级别]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4737338</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4737338</guid><author>Trance</author><pubDate>Wed, 28 Oct 2009 11:10:00 +0800</pubDate><description><![CDATA[SET TRANSACTION ISOLATION LEVEL{READ UNCOMMITTED| READ COMMITTED| REPEATABLE READ| SERIALIZABLE}一、未提交读READ UNCOMMITTED（脏读）意义：包含未提交数据的读。例如，在多用户环境下，用户B更改了某行。用户A在用户B提交更改之前读取已更改的行。如果此时用户B再回滚]]></description><category></category></item><item><title><![CDATA[DB2系统目录表]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4732969</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4732969</guid><author>Trance</author><pubDate>Tue, 27 Oct 2009 12:30:00 +0800</pubDate><description><![CDATA[每个数据库都有它自己的系统目录表和视图。它们存储关于数据对象的元数据。你可以像使用普通的数据库表一样查询这些表。有三种模式用来识别系统目录表： • SYSIBM: 基本表， 对 DB2使用进行最优化 • SYSCAT: 基于SYSIBM表的视图， 对平常轻负荷使用进行优化 • SYSSTAT: 数据库分析  下面是一些目录视图的例子  • SYSCAT.TABL]]></description><category></category></item><item><title><![CDATA[序列对象]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4732967</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4732967</guid><author>Trance</author><pubDate>Tue, 27 Oct 2009 12:29:00 +0800</pubDate><description><![CDATA[ 序列对象产生整个数据库的一个唯一值。跟标识列不一样的是，序列独立于数据表：CREATE TABLE t1 (salary int) CREATE SEQUENCE myseq    START WITH 10    INCREMENT BY 1    NO CYCLE INSERT INTO t1 VALUES (nextval for myseq) IN]]></description><category></category></item><item><title><![CDATA[重建索引]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4732964</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4732964</guid><author>Trance</author><pubDate>Tue, 27 Oct 2009 12:29:00 +0800</pubDate><description><![CDATA[ declare id intset id=object_id()dbcc showcontig(@table_id)go--重建单个索引dbcc dbreindex(, , 90)go--重建数据库中所有索引EXEC sp_msforeachTable @Command1=" DBCC DBREINDEX (?,,80)"   -- 可以选]]></description><category></category></item><item><title><![CDATA[B树、B-树、B+树、B*树]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4732886</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4732886</guid><author>Trance</author><pubDate>Tue, 27 Oct 2009 12:00:00 +0800</pubDate><description><![CDATA[B树       即二叉搜索树：       1.所有非叶子结点至多拥有两个儿子（Left和Right）；       2.所有结点存储一个关键字；       3.非叶子结点的左指针指向小于其关键字的子树，右指针指向大于其关键字的子树；       如：              B树的搜索，从根结点开始，如果查询的关键字与结点的关键字相等，那么就命中；否则，]]></description><category></category></item><item><title><![CDATA[DBCC SHOWCONTIG说明]]></title><link>https://blog.youkuaiyun.com/Trance/article/details/4732882</link><guid>https://blog.youkuaiyun.com/Trance/article/details/4732882</guid><author>Trance</author><pubDate>Tue, 27 Oct 2009 11:59:00 +0800</pubDate><description><![CDATA[原文：http://www.cnblogs.com/petitprince/archive/2009/10/23/1588603.html DBCC SHOWCONTIG是显示指定的表的数据和索引的碎片信息。 解释如下： Page Scanned-扫描页数：如果你知道行的近似尺寸和表或索引里的行数，那么你可以估计出索引里的页数。看看扫描页数，如果明显比你估计的页数要高，]]></description><category></category></item></channel></rss>