SQL Tutorials

Differentiate between Primary key and Foreign key

Primary Key Foreign Key It identifies the each record in a table uniquely. It maintains the relation between two tables. A foreign key is primary key in another related table. A table can have only one Primary key. A table can have more than one Foreign key. Primary key cannot have NULL values. Foreign key […]

Differentiate between Primary key and Foreign key Read More »

Differentiate between Database state and database schema

Database Schema Database State Database Schema represent overall design of the database. Database state represent current state of data in database. Database schema is changed ocassionally Database state is changed frequently Initially when defining a database, only Database schema is specified Initially when defining a database, database state is empty state.

Differentiate between Database state and database schema Read More »

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

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 !!