How do you define a composite primary key?

A composite primary key, also called a composite key, is a combination of two or more columns to form a primary key for a table….2. Composite Primary Keys

  1. The composite primary key class must be public.
  2. It must have a no-arg constructor.
  3. It must define the equals() and hashCode() methods.
  4. It must be Serializable.

What is a composite primary key give an example?

A primary key having two or more attributes is called composite key. It is a combination of two or more columns. An example can be − Here our composite key is OrderID and ProductID − {OrderID, ProductID}

What is composite key class 10th?

Composite Key The composite key refers to a set of multiple attributes that help us uniquely identify every tuple present in a table.

What is primary key and composite primary key?

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.

What is composite key Mcq?

Composite Key: A key that consists of more than one attribute to uniquely identify rows (also known as records & tuples) in a table is called composite key. Foreign Key: Foreign keys are the columns of a table that points to the primary key of another table. They act as a cross-reference between tables.

What is composite primary key in SQL Server?

When two or more Columns are together Identify the unique row in a table Known as Composite Primary Key. A composite key is a key that is the combination of more than one attribute or column of a given table. It may be a candidate key or a primary key.

What is primary key Mcq?

Explanation: The primary key is a single or combination of the field that identifies each record in a table uniquely. It cannot take a NULL value. A table can have only one primary key.

What is a composite table SQL?

The Composite Key in SQL is a combination of two or more columns, which are used to identify the rows from a table. Here individually the specified columns will not be unique, the combination of the columns gets the uniqueness and able to fetch data from the table.