2009年2月25日星期三

February 26th-27th Links:SQL SERVER,ASP.NET PERFORMANCE

C#
    1. Creating SOLID Code: Sigle Responsibility Principle- Episode-Codebetter.com 

ASP.NET

IIS

SQL SERVER
    The query statement is related Table : sys.foreign_keys,sys.foreign_key_columns,sys.objects
    Third Normal Form(3NF) is most preferable normal form in RDBMS.Nomalization is the process of designing a data model to efficiently store data in database.The rules of 3NF are mentioned here:
    1) Make a sperate table for each set of related attributes, and give each table a privary key.
    2) If an attribute deponds on only part of a muil-valued key. remove it to a separate table.
    3) If an attribute don't contribute(有助) to a description of the key, remove it to a separate table.
    Normalization is very close to concept of Object Oriented schema's and it stores one data at only one place by removing all the redundant(多余的) data. Normalization comes at cost of performance.
    PS: 1NF: 数据库表中的字段都是单一属性,不可再分.
           attribute1   attribute2  attribute3(attribute3.1,attribute3.2...)
           2NF: 数据库表中不存在非键字段对任一候选关键字段的部分函数依赖.
           (studentId, courseName)->(studentName,age,grade,credits(学分))
           but
           (courseName)->(credits)
           (studentId)->(studentName,age)
           3NF: 数据表中不存在非关键字段对任一候选关键字段的传递函数依赖。
          (studentId)->(name,age,college,colleagePhone,colleageLocation)
   but
          (studentId)->(colleage)->(colleagePhone,colleageLocation)

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