What is happened when we create a field a primary key?
Manoj Kalla
if primary key created internally clustered index will be created
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.
Primary key mustn't have Null values.And it can be an object of table that can be used in other tables.
Primary key is identification of record
Clustered index will be created for that field.
If we declare column name as primary key then that column will not accept null values.
When creates a primary key then internally created clustered Index.
when you declare a column as primary then that column become clustered index key automatically
when we create a field with primary key id Duplicate records in the table is avoided
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.
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.
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
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.
Only Not Null and Unique values are allowed in the field to which a primary key is applied.
to avoid duplicate value and it it identified unique value in table.