Thursday, 23 June 2016

Question and Answers in Sql Server - Part 17

In This post Let we see some important question and answers in Sql Server, which is a continuation of previous post.

65. What is E-R Diagram ?
       An E-R Diagram is a graphical representation of  the inter relationship between the Entities in a database. Table is an Entity  ex: Employee table is an Entity

      An E-R Diagram Consists of an Following Elements.
      1. Entities      [Table   i.e Employee]  
      2. Attributes  [Columns i.e Employeeid,Name,Salary]
      3. Relationships [relationship between two tables]  , i.e three types One-One,One-Many,Many-Many

       One-One :  Person table - Passport table
       One - Many : Student - Subjects
       Many - Many : Customer - Order

66. What is Policy Based Management [PBM] ?
      Policy Based Management is a new feature in SQL Server 2008 that enables database administrators to  create and enforce policies to configure and manage SQL SERVER. A policy is a Rule that specifies a certain conditions to be evaluated against a managed Target.

       Following are the basic terms in PBM
      1. Managed Target
      2. Facet
      3. Condition
      4. Policy
      5. Policy Category
      6. Effective Policy

     Managed Target : A Managed Target is an Entity on which you want to apply policy. Ex Sql Server instance, Schema, Database etc.

     Facet :  Facet is set of properties that model the behavior and characteristics of a managed target.

    Condition : A condition is a one or more clauses that specify properties of a facet.

    Policy : A Policy contains the condition that specifies how to set the properties of the facet of a managed target.

    Policy Category : we can group the policy into different policy types known as policy categories.A policy can be belong to only one category. we can create policy categories at server level or database level.

    Effective Policy :  A Policy is considered to be effective policy if:
     1. Policy is Enabled
     2. The managed target belongs to the set of managed targets targeted by the policy.
     3. The managed target or one of its ancestors subscribes to the policy category that contains the policy.

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