Tuesday, 13 December 2011

what's benefits of using index in sql server or oracle ....................

Actually i want to no why we use the indexes in sql server   i want to know 

2 comments:

  1. Now I m Going To Explain the Topic Index in sql server , Which May be Help full To All If Any One Has Some Better Explaination Then Explain It

    Index Is Used To Incease The Peformace Of Data Base As Every Organisation Has Its DataBase Which Stores Records As Data Increase In data Base Its Performance Reduce . Now To Mantain The Performance Of Data Base We Use The Indexes In dataBase Or On Our Table

    Genral Syntex To create Index:

    Create [IndexType] Index on (ColumnName)

    Where IndexType Means Type Of Index Weather Unique,Clustered And Non Clustered

    IndexName Is The Name Of Index

    TableName Is The Name Of The Table On Which U Wann To Create Index

    ColumnANme Is The Name Of Column Which Becomes Index For The Table

    There Are Two Three Types Of Indexes:

    1) Unique Index
    2) clustered Index
    3) Non Clustered Index

    Unique Index :

    We Can Create Unique Index Simply By Using Query

    create Unique index indexName On TableName(ColumnName)

    Unique Index Means , A Index Which Does Not Allow Same Index For More Then One Data Row Means No Two Data Row Can Have Same Index Beside It We Can Not Create Unique Index If Data Row Has Duplicate Value

    Clustered Index:

    We CAn Create The Clustered Index Simply By Using Query as

    Create Clustered Index IndexName on TableName(ColumnName)

    A Clustered Index Just create index In Which the logical order just points to the physical oreder of the data rows in data table and this index is created with in data table And The Physical Order Of The DataRows Is Dependent Of The Logical Ordering(Index).

    Non Clustered Index:

    we Can Create Non Clustered Index As

    Create NonClustered Index IndexName On Table(Column)

    Unlike Clustered Index, In Non Clustered Index The Physical Order of Table Is Independent of Index
    Actually, Clustered Index Create a Logic Order Which Identyfy The Physical Order Of Data rows In Table And The LOgic Order Order Is Stored Independent Of The Table Means Any Where On The Disk

    We Can Drop The Index If It Requered After Its Creation as

    Drop Index Table.IndexName

    Here Its Neccessary To Defined The Index Name With The Table Names

    We Can Rename The Created Indexes By Using The Existing Stored Procedure as

    EXEC sp_rename 'table.oldIndexName','NewIndexName'

    Here sp_rename is inbuelt stoed procedure Which Takes Two Parameters First The Index Name With The Table Name Which Is To Be renamed and Second New Index NAme

    We Can See The Currently Created Index On Any Table By Using The Inbuelt Stored Procedure as

    Exec sp_helpindex table

    This Stored Procedure Is Inbuelt Stored Pocedure Which Takes Only One Parameter Which Is Table NAme
    And It Gives Coplete Information Of The Indexes Used On The Table

    There Is Another Important InBuelt Stored Procedure Which Gives Complete Information About The Table sp_help it takes only one parameter which is table name

    exec sp_help table

    now it gives complete information about the table passed as parameter

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  2. One of the most important routes to high performance in a SQL Server database is the index. Indexes speed up the querying process by providing swift access to rows in the data tables, similarly to the way a book’s index helps you find information quickly within that book.

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