8. What are disadvantages of using Relational Database?
- Cost – Relational database are quite expensive, small businesses can’t afford and support is expensive too
- Storage – These requires huge physical storage due to rows and columns structure
- Tedious Maintenance – With growing volume, the database becomes difficult to maintain
- Lack of Scalability – When you scale it up in multiple server, there are latency issues, performance issues
- Lack of Flexibility – These DBs can’t handle large amount of unstructured data.
- Slow – These are slow in extracting data from database as compared to other databases.
9. What are benefits or advantages of using Non Relational Database or NoSQL Databases?
- Flexibility – NoSQL database can store data in structured, unstructured and semi-structured format.
- Scalability – It is easily scalable horizontally using virtual environment and less cost incurred. Ideal for BigData.
- Freedom of Datatypes– There is no pre-defined schemas so we can adapt to new data types easily for storing of new types of data.
- Less Code – It requires very few lines of code ideal for developer
- Easy Database Maintenance – It can automatically partition and replicate data across nodes reducing dependencies on DBA resources.
- Less Costly – inexpensive commodity hardware can be used to set up cluster of servers to hold large volume of data.
- High Availability – It does automatic replication of data across data centers, cloud resources or multiple resources and reduce latency significantly for users
10. What are disadvantages of using NoSQL Databases?
- ACID(Atomicity, Consistency, Isolation, Durability) properties are not supported by NoSQL Databases. They rather depend on ‘eventual consistency’.
- NoSQL databases are not 100% compatible with SQL
- NoSQL databases lack standardization, each having own rules of engagement.
- Lack of database management tools in these type of DBs.
- They don’t have an uniform programming language, each NoSQL DBs have their own.
11. What are different types of SQL Queries?
- DDL – Data Definition Language
- DQL – Data Query Language
- DML – Data Manipulation Language
- DCL – Data Control Language
- TCL – Transaction Control Language
| DDL Queries | DQL Queries | DML Queries | DCL Queries | TCL Queries |
| CREATE | SELECT | INSERT | GRANT | COMMIT |
| DROP | UPDATE | REVOKE | ROLL BACK | |
| ALTER | DELETE | SAVE POINT | ||
| TRUNCATE |
12. What do you mean by DBMS? What are the different types of DBMS?
A Database Management System (DBMS) Software is designed to store, retrieve, manage and define data in a database. It manages the database engine, database schema and works as an interface between user and database.
Types of DBMS
- Hierarchical Database
- Network Database
- Relational Database
- Object Oriented Database
Hierarchical – Data is stored in top -down or bottom -up approach. One parent with many children and many children can have only one parent
Network – Many-to-many relationship exist between parent and child tables.
Relational – Deals with normalizing data in rows and columns in a table
Object Oriented – Data is stored in the form of objects.