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What does a primary key do?
A primary key is a unique identifier for a record in a database table, ensuring that each entry is distinct and can be accurately referenced. It prevents duplicate records and enforces data integrity by establishing a reliable way to access and manipulate data. Additionally, a primary key can facilitate relationships between different tables in a relational database.
How is the primary key used?
It is used as the unique identifier for each record and is used to sort the data
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 a primary key is fixed in a sql table?
A primary key field in a sql table is created using the PRIMARY KEY keyword. ex: CREATE TABLE tbl_employee ( emp_num VARCHAR(10), emp_name VARCHAR(100), PRIMARY KEY (emp_num)) The above script creates a table called tbl_employee and sets the emp_num field as the primary key
In a data base the primary key field is used to?
uniquely identify a record
Does a primary key maps an entire database?
yes a primary key can map the whole data base because if we take the example of any employee table in which ssn is the primary key with the help of this key we can determine that employee name and where he works on & which post ,his or her post,department no,location etc. so i think it can be true.
Does a primary key have to be an integer in an Access database?
No, it does not. A primary key can be different types of data, not just an integer.
What are the properties of primary key?
data cannot be repeated
How can a primary key be useful in controlling data redundancy?
controlling data redundancy
What is the primary key field of a database?
its a unique key use to identify data in database
How can you apply the primary key?
Primary key is the one which is uniquely defined in the attributes of a table. It can be used to pull any kind of data regarding a particular tuple in the table. PRIMARY IS ALSO A CANDIDATE KEY.
Does the data in a primary key field common to all records?
Yes
What is the condition for a key to be a foreign key?
A key is considered a foreign key if it references the primary key of another table to establish a relationship between the two tables. It enforces referential integrity, ensuring that data in the foreign key column corresponds to data in the primary key column.
primary key?
attribute of an entity which uniquely identifies a specific instance of the data
What is the difference between a primary key and a foreign key?
A primary key uniquely identifies each record in a table and ensures data integrity. A foreign key establishes a relationship between two tables, referencing the primary key of another table to enforce referential integrity.
What is a primary key what is its purpose and why do you use it?
What is a Primary Key?The PRIMARY KEY constraint uniquely identifies each record in a database table.Primary keys must contain unique values.A primary key column cannot contain NULL values.Each table should have a primary key, and each table can have only ONE primary key.The primary key is defined by using the PRIMARY KEY constraint when either creating a table or altering a table.*Example of primary key :- customer Nowhat is its purpose and why do you use it?In relational database design, a unique key or primary key is a candidate key to uniquely identify each row in a table.
