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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 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.
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.
Does primary key allow null?
No
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.
Can a pri Mary key have a null value?
No, a primary key cannot have a null value. A primary key is used to uniquely identify each record in a database table, and having a null value would violate this uniqueness requirement. Therefore, every primary key must contain a unique, non-null value for each record.
Have all tables primary key?
No, all tables do not have primary key. Primary must be explicitly defined and must not be null.
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...
Can a primary key refer to a whole table?
No, a primary key do not refers to the whole table .A primary key refers to a field in the table that is not null and unique.
What are properties of a primary key?
The properties of primary key are as follows: 1. It should be unique. 2. It should be not null.
Is alternate key have null value?
An alternate key is a set of one or more attributes that can uniquely identify a record in a database table, similar to a primary key. However, unlike a primary key, an alternate key can accept null values, as its primary purpose is not to enforce uniqueness in the same way. That said, if an alternate key is defined on a column that allows nulls, only one null value can exist in that column to maintain uniqueness among non-null entries.
