SQL

• Relational Databases
• Table based
• Predefined schema
• Vertically scalable
• SQL (structured query language)
• MySql, Oracle,Sqlite, Postgres & MS-SQL
• Best fit for heavy duty transactional type application
• Excellent Support are available
• emphasizes on ACID properties ( Atomicity, Consistency, Isolation and Durability)
• we can classify SQL databases as either open-source or close-sourced from commercial vendors

NoSQL

• Non- relational Databases
• Document based, key-value pairs, graph or wide-column
• Dynamic schema
• Horizontally scalable
• No SQL
• MongoDb, BigTable, Redis, RavenDb, Cassandra, Hbase
• still not comparable and sable enough in high load and for complex transactional applications
• Rely on community support
• follows the Brewers CAP theorem ( Consistency, Availability and Partition tolerance )
• can be classified on the basis of way of storing data as graph databases, key-value store databases, document store databases, column store database and XML databases.