What is data?
In layman's terms, data are facts about any object. For example, your age, jobs, house number, contact number, and name and location are all data about you.
What is a database?
A "database" is a synthetic collection of stored and manipulated data.
e.g., Facebook, telecom companies, Amazon.com
What is a DBMS?
A database management system (DBMS) is a collection of programmes that allow users to access databases, manipulate data, report on data, and represent data.
Types of DBMS:
1) Hieranchical
2) Network
3) Relational
4) Object-oriented
1) Relational Database
A relational database is a data structure that allows you to link information from different tables or different types of data buckets.
Tables are related to each other.
All fields must be filled.
-Ideal for OLTP (online transaction processing).
Relational databases include My SQL, Oracle, DBMS, and IBM DB2.
A table row is also known as a record.
- Contains information about each individual entry in the table.
Each table had its own primary key.
A schema is used to strictly define table, column, index, and relations between tables.
Real-time DBs are usually used in enterprise application scenarios.
- MySQL, which is used for web applications, has an exception.
eg.JOOMLA
- Can not scale - out horizontally
- SQL is used in almost all relational databases.
2) Non-relational DB (no SQL database)
Non-relational databases store data without a structural mechanism to link data from different tables to one another.
- Require low-cost hardware.
- Significantly faster performance (read/write) than relational DBS.
- Never provide a table with a flat, fixed-column record. It means schema-free.
- Ideal for online analytical processing
- Examples include NoSQL databases such as MongoDB, CalSandra, DynamoDB, PostgreSQL, and Raven Redis.
Types of SQL Databases:
Columnar database (Cassandra, HBase)
Document Database (MongoDB, CouchDB, RavenDB)
Key Volume Database (Redis, Riak, DynamoDB, Tokyo Cabnet)
1) Columnar Database
A columnar database is a DBMS that stores data in columns instead of rows.
In a columnar database, all the column 1 values are physically together, followed by all the column 2 values.