MCQ IN COMPUTER SCIENCE & ENGINEERING

Detailed explanation-1: -Primary key-A primary key is a field in a table that contains unique data. Which of these data items are unique? There is a short cut to writing out database table designs, where the underlined attribute is the primary key. Note that primary keys are normally written first.

Detailed explanation-2: -The primary-key attribute and a value assigned to a record becomes the primary key of the record. Every record added to the data store must have a primary key. The primary-key attribute type can be of any supported Dgraph property types. The name of the primary-key attribute must be in an NCName format.

Detailed explanation-3: -Make sure you identify a primary key for each table and all foreign keys. If necessary, you can add an attribute to use as the primary key. Primary keys should be underlined, and foreign keys should have a dashed underline.

Detailed explanation-4: -The primary key is an attribute or a set of attributes that uniquely identify a specific instance of an entity. Every entity in the data model must have a primary key whose values uniquely identify instances of the entity.