What are different types of keys in DBMS?

What are different types of keys in DBMS?

Keys are of seven broad types in DBMS:

• Candidate Key.
• Primary Key.
• Foreign Key.
• Super Key.
• Alternate Key.
• Composite Key.
• Unique Key.

What are the different types of keys?

Types of keys:

• Primary key. It is the first key used to identify one and only one instance of an entity uniquely.
• Candidate key. A candidate key is an attribute or set of attributes that can uniquely identify a tuple.
• Super Key.
• Foreign key.
• Alternate key.
• Composite key.
• Artificial key.

What are the different types of keys explain any two of them?

There are different types of the keys available….

• Sunk Keys. Sunk Keys.
• Saddle Keys. These type of keys are rarely used because these cannot transmit the high torque.
• Tangent Keys. Tangent Keys.
• Round Keys. Round keys are circular in section and fit into the holes.
• Splines. Splines.

What is primary key and example?

A primary key is a column — or a group of columns — in a table that uniquely identifies the rows of data in that table. For example, in the table below, CustomerNo, which displays the ID number assigned to different customers, is the primary key. CUSTOMERS. CustomerNo.

What are keys in a database?

A key is a field, or combination of fields, in a database table used to retrieve and sort rows in the table based on certain requirements. Keys are defined to speed up access to data and, in many cases, to create links between different tables.

What is composite key give an example?

In a table representing students our primary key would now be firstName + lastName. Because students can have the same firstNames or the same lastNames these attributes are not simple keys. The primary key firstName + lastName for students is a composite key.

What is composite key in DBMS with example?

A composite key is the DBMS key having two or more attributes that together can uniquely identify a tuple in a table. Such a key is also known as Compound Key, where each attribute creating a key is a foreign key in its own right.

What is candidate key in database with example?

Candidate Key: The minimal set of attributes that can uniquely identify a tuple is known as a candidate key. For Example, STUD_NO in STUDENT relation. It is a minimal super key. It is a super key with no repeated data is called a candidate key. The minimal set of attributes that can uniquely identify a record.

What is a primary key example?

A primary key is a column — or a group of columns — in a table that uniquely identifies the rows of data in that table. For example, in the table below, CustomerNo, which displays the ID number assigned to different customers, is the primary key.

What is super key with example?

Super Key: The set of attributes that can uniquely identify a tuple is known as Super Key. For Example, STUD_NO, (STUD_NO, STUD_NAME), etc. rows in a table. * It supports NULL values.

What is partial key in DBMS with example?

Partial Key : The set of attributes that are used to uniquely identify a weak entity set is called the Partial key. Only a bunch of the tuples can be identified using the partial keys. The partial Key of the weak entity set is also known as a discriminator.