Manoj Kalla
What is happened when we create a field a primary key?
By Manoj Kalla in SQL Server on Jan 04 2016
  • Rameshyadav Medaboina
    Jun, 2016 24

    if primary key created internally clustered index will be created

    • 2
  • Rameshyadav Medaboina
    Jun, 2016 24

    if primary key created internally clustered index will be created

    • 1
  • Anil Kumar Murmu
    Jan, 2016 13

    Primary key is a combination of unique key constraint and clustered index. Behind the scene, it cares of 2 things: It does not all NULL to be inserted into column and secondly, it takes care of physical ordering of Data. In data base when we create a Primary Key on any table for a specific column. If we go to Object Explorer, we can see a unique key and a clustered index has been added to table.However, it also include NOT NULL constraint along with Unique key constraint.

    • 1
  • Rafnas T P
    Jan, 2016 8

    A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values.A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.If a table has a primary key defined on any fields, then you can not have two records having the same value of that fields.

    • 1
  • Joe Wilson
    Jan, 2016 7

    Primary key mustn't have Null values.And it can be an object of table that can be used in other tables.

    • 1
  • Mahesh Gawhane
    Jan, 2016 7

    Primary key is identification of record

    • 1
  • Manoj Kalla
    Jan, 2016 4

    Clustered index will be created for that field.

    • 1
  • Khaja Moizuddin
    Dec, 2016 2

    If we declare column name as primary key then that column will not accept null values.

    • 0
  • Vijay Dhiman
    Aug, 2016 25

    When creates a primary key then internally created clustered Index.

    • 0
  • sushil kumar
    Jun, 2016 8

    when you declare a column as primary then that column become clustered index key automatically

    • 0
  • Melbin m p
    Feb, 2016 12

    when we create a field with primary key id Duplicate records in the table is avoided

    • 0
  • Anil Kumar Murmu
    Jan, 2016 13

    Primary key is a combination of unique key constraint and clustered index. Behind the scene, it cares of 2 things:It does not all NULL to be inserted into column and secondly, it takes care of physical ordering of Data.In data base when we create a Primary Key on any table for a specific column. If we go to Object Explorer, we can see a unique key and a clustered index has been added to table.

    • 0
  • Kml Surani
    Jan, 2016 9

    Primary key mustn't have Null values.And it can be an object of table that can be used in other tables.

    • 0
  • Mahaveer Yadav
    Jan, 2016 9

    If we create a field with primary key that means ,we can not insert duplicate value and null value and by default clustered index is created on that field

    • 0
  • Rafnas T P
    Jan, 2016 8

    A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values.A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.If a table has a primary key defined on any fields, then you can not have two records having the same value of that fields.

    • 0
  • bharat aggarwal
    Jan, 2016 6

    Primary key is used to identify records in table uniquely and it won’t allow null values and duplication of data. Only one primary key is allowed for each table.

    • 0
  • Jainish Shah
    Jan, 2016 6

    Only Not Null and Unique values are allowed in the field to which a primary key is applied.

    • 0
  • manoj kumar
    Jan, 2016 6

    to avoid duplicate value and it it identified unique value in table.

    • 0


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