fyifei0558的专栏

MySQL:1. avoid full table scan, so please consider to create index on the column of where, orderby2. avoid null value check 应尽量避免在where子句中对字段进行null值判断，否则将导致引擎放弃使用索引而进行全表扫描，如：select id from t where num is null可以在num上设置默认值，确保表中num列没有null值，然后再如下查询selec.

http://technet.microsoft.com/en-us/library/cc293613.aspx Note:the duration is micro-second, not milli-second We can create template viaForstored procedure investigation, we just chec

I ran into the issue on SQL server.:INSERT failed because the following SET options have incorrect settings: 'QUOTED_IDENTIFIER'.I checked all stored procedures: it is "SETQUOTED_IDENT

http://www.sqlnotes.info/2012/01/13/are-jobs-currently-running/Are jobs currently running? This question is asked very frequently by DBAs. The simplest answer is to use SSMS, navigate to SQL Ser

sql server http://www.yesky.com/imagesnew/software/tsql/ts_sp_da-di_9qlv.htm

这个可以帮做我们看目前哪些stored procedure在运行，或者挂起SETTRANSACTIONISOLATIONLEVELREADUNCOMMITTED-- What SQL Statements Are Currently Running?SELECT [Spi

自带的工具有 ：1. Activity monitor2. select "DB instance"-->right click, report-->standard report-->user statistic.3. DMV4. SELECT login_name ,COUNT(session_id) AS session_count FROM sys.dm_exec_sess

http://blogs.msdn.com/b/craigfr/archive/2006/06/30/652639.aspx RID lookup

1.  Implicit Conversion will cause index scan instead of index seek. SELECT aFROM dbo.TeletedAS GP WHERE principalId =@tempNote: principalId date type is uniqueidentifier; but the @t

mysqlhttp://dev.mysql.com/downloads/mysql/#downloads Issue: When I install mysql on my centos 7 with yum, it complain the following error:Solution: Just remove the mariadb-libsvia the

http://blog.itpub.net/26230597/viewspace-1098147/参考资料 reference:  http://mongodb.blog.51cto.com/1071559/740131  http://docs.mongodb.org/manual/tutorial/deploy-shard-cluster/#sharding

Cassandra中的各种策略http://dongxicheng.org/nosql/cassandra-strategy/1. 背景介绍Cassandra 使用分布式哈希表（DHT）来确定存储某一个数据对象的节点。在 DHT 里面，负责存储的节点以及数据对象都被分配一个 token。token 只能在一定的范围内取值，比如说如果用 MD5 作为 token 的话

Cassandra Query Language (CQL) v3.4.2Cassandra Query Language (CQL) v3.4.2CQL SyntaxPreambleConventionsIdentifiers and keywordsConstantsCommentsStatementsPrepared StatementData Definit

/*sql xml 入门:    --by jinjazz    --http://blog.youkuaiyun.com/jinjazz        1、xml:        能认识元素、属性和值        2、xpath:    寻址语言，类似windows目录的查找(没用过dir命令的话就去面壁)  

select*fromsys.dm_exec_sessionswherehost_nameisnotnullandstatus='running'

http://blog.sina.com.cn/s/blog_3fe961ae010139u6.html传统关系型数据库面临的挑战l High Performance——对数据库高并发读写的需求l Huge Storage——对海量数据的高效率存储的需求l High Scalability & High Availablity——对数据库的高可扩展性和高可用

Create procedure ordertotal        @order_total money outputasbeginselect @order_total = sum(item_price*quantity) from oders where .....end@order_total定义为OUTPUT，因为要从存储过程返回合计值  调用它：

USE Test;     ALTER TABLE TestTable   ADD col3 int;     INSERT INTO TestTable   (col1, col2, col3)   VALUES   (1,1,1); We will get a error information. SQL Server can't reconginize the column, so

DECLARE @SchemaName varchar(128)  DECLARE @TableName varchar(128)   -- Now, grab the table name that goes with our ID  SELECT @SchemaNameSchemaName = SchemaName, @TableNameTableName = TableName  FRO

Chapter 9批处理和脚本脚本里可以包含多个批处理。它们之间用GO分开。But one SQL batch only has one ‘Go’.SQL Batch 是T-SQL 语句集合的逻辑单元。Note: ‘ Go’ is not a T-SQLcommand.GO’s definition:1.      独立成行2.      独立发送批处理到服务器

1.  在运行中输入“services.msc”,然后确定如图： 2.进入到服务面板

1.  看图： 2. 进入SQL server 2008 3. 进入SQL server 2008, 准备修改： 4.进入属性面板，并且选择“security”,看图 5. 单击“New Query”   6.复制下面的代码到如图所示，然后单击"Execute",  use master ALTER LOGIN sa ENABLE

http://www.cnblogs.com/zsjtianya/archive/2012/06/24/2559736.html (2)对cnblogs的这篇文章,进行一点补充,第三步写的不够明白.1介绍组件   1).Foreach Loop Container   2).Execute SQL Task2.功能介绍  1).Foreach Loop Contai

http://www.katieandemil.com/ssis-lookup-transformation-example-sql-server In this tutorial I will explain and give a simple example of SSIS lookup transformation.Let's start with short explanati

http://stackoverflow.com/questions/13730531/whats-the-difference-between-error-output-and-no-match-output-in-lookup-trans  1down voteacceptedWith the Lookup Transformation in SSI

https://www.simple-talk.com/sql/sql-tools/how-to-identify-blocking-problems-with-sql-profiler/How to Identify Blocking Problems with SQL Profiler13 March 2009by Brad McGeheeMany SQL Server

1. change the database mode from full to simple2. start shrink.

1.  通过profiler去capture several minutes data;2.  see which store procedure takes much time (for example, the store procedure take 6.5 seconds)3. via the execution plan to analyze which SQL sentence

Installed on Windows server 2008(64bit), please use 64bitlegacy installation package.the steps is fromhttp://blog.sina.com.cn/s/blog_685213e70101g81t.html安装MongoDB1.按照操作系统下载http://

临时表分为:本地临时表,仅限于当前访问者访问,创建方法去如下:create table #TableName(表结构)储存于数据库tempdb内(硬盘),当前用户断开连接,自动删除如果使用中不断开连接,且不需要该临时表请执行:drop table #TableName全局临时表,所有访问用户访问,创建方法去如下:create table ##TableName(表结构)