Database Schema
The database schema is the skeleton structure of the database that provides the logical view of the whole database. It describes how data are organized and how they relate. It outlines all constraints that must be applied to the data.
A database schema describes the relationships between entities. A schema diagram can show you the details of the database. Database designers design schemas to aid programmers in understanding the database and making it useful.
Two categories can be used to group a database schema:
1.Physical Database Schema- This schema refers to data storage and the form of storage such as files or indices. This schema defines the storage method for data in secondary storage.
2.Logical Database Schema- This schema defines all the logic constraints that must be applied to the data stored. It includes views, tables, and integrity restrictions.
Database Instance
These two terms should be distinguished separately. The database schema is the basis of a database. It is created when the database does not exist. It is difficult to make changes once the database is operational. A database schema doesn't contain any data.
A database instance is an operational state that contains data at any time. It is a snapshot of the database. The database instances change over time. By following the strict validations, constraints and conditions set by the database designers, a DBMS can ensure that every instance (or state) is valid.
Continue reading to learn about SEO
1. How to Improve SEO Performance with Professional Services
4. How to get organic website traffic
6. SEO
8. SEO TOOLS
9.SCHEMA
10. MIX
2.1.png)
5 Comments
your information is very good
ReplyDeleteThank you sir
Deletenice post
ReplyDeleteThank you sir
DeleteThis comment has been removed by a blog administrator.
ReplyDelete