Database Concept

Why foreign keys are allowed to have NULL values? Explain with an example.

Leave a Comment / CS Class 12 Tutorial, Database Concept, IP Class 11 Tutorial, IP Class 12 Tutorial, NCERT Solutions, SQL Practicals /

Foreign Key is used to represent the relation between two tables. Because in the field with Foreign key attribute data comes from Primary key field in another related table and so Foreign key are allowed to have Null Values if it not the part of Primary key field of the related table. For example- Here […]

Why foreign keys are allowed to have NULL values? Explain with an example. Read More »

1. Give the terms for each of the following:
Collection of logically related records.

CS Class 11, CS Class 12 Tutorial, Database Concept, IP Class 11 Tutorial, IP Class 12 Tutorial, NCERT Solutions, RDBMS, SQL Tutorials /

a) Collection of logically related records.b) DBMS creates a file that contains description about the data stored in the database.c) Attribute that can uniquely identify tuples in a relationd) Special value that is stored when actual data value is unknown for an attribute.e) An attribute which can uniquely identify tuples of the table but is

1. Give the terms for each of the following:
Collection of logically related records. Read More »

error: Content is protected !!