0
No. A primary key requires a value because it is the field that all other values in the row depend on.
Wiki User
∙ 12y ago
Add your answer:
Earn +20 pts
What does the primary key in a data base do?
We know that primary key is the one that is not null and is always unique. A primary key uniquely identifies a record in a table.
Candidate key and primary key differnece?
All Primary keys are definitely Candidate Keys. A Candidate key is one which can be used as a Primary key that is not null and unique. That is one of the candidate keys can be chosen as a primary key.A Candidate key is a Unique Key and it can be used to find out any particular Tuple (row) in a table. The following are the differences between A Candidate key and a Primary Key: 1) A Unique key can be null but not a Primary key 2) On a table we can have only 1 primary key but 'N' number of unique keys.
What is primary key constraint?
Primary Key is a Constraint Used to avoid Duplicate entries in database table and you define primary key the column doesn't allow NULL values.
How do you Avoid missing column values for non primary key columns?
Use Default and Not NULL
Can Super key be null?
why there is no answer yet
Can a primary key have a blank or null value entered into its cell?
No. A Primary Key is the Unique identifier and cannot be null and cannot be duplicate.
Entity integrity constraint?
The entity integrity constraint states that no primary key value can be null. This is because the primary key value is used to identify individual tuples in a relation. Having null value for the primary key implies that we cannot identify some tuples. This also specifies that there may not be any duplicate entries in primary key column key row.
Is a primary key a unique identifier?
NO, unique identifier allows null values.. so u dont called as primary key... primary key means it doesn't allow null n repeated values.... so we dont call unqiue identifier is a primary key...
What is primery key?
primary key is a column or set of columns (called composite primary key ) that identify the table & make every table unique .value of a primary key can not duplicated & can not be NULL .
How you create or assign primary key?
A primary key is never null and is also unique . Example of primary key is create table emp (ecode integer NOT NULL PRIMARY KEY);
What is a primary key that is null?
Unique key
What not a likely primary key?
A field that is not unique and null can not be used as a primary key. Praimary key must satisfy the conditions of not null and unique.
What are the advantage of primary key?
Primary key that is used to identify a record uniquely. Primary key is a key that always unique and not null. A system generated primary key is called surrogate key.Primary key is the one which is always unique and not null. Advantage of primary key that it helps in identifying a tuple uniquely.
Does primary key allow null?
No
What rule states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null?
referential integrity constraint
What does the primary key in a data base do?
We know that primary key is the one that is not null and is always unique. A primary key uniquely identifies a record in a table.
What are field can be used as primary key?
A field or set a of fields Êin a database tableÊwith unique values Êcan be used as a primary key.ÊPrimary key field cannot have a null value.
