PROJECTION and SELECTION are the unary operations in relational algebra. Unary operations are those operations which use single operands. Unary operations are SELECTION, PROJECTION, and RENAME.

As in SELECTION relational operators are used for example - =,<=,>=, etc.

It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties

1. Minimizing redundancy,

2. Minimizing insertion, deletion and update anomalies.  

There have several kinds of languages available in DBMS, please find below details:

• DDL: DDL is defined as data definition language. This is used to give some proper definition of the database and schema maintaining some schema structure properly by using create, truncate, alter, rename and drop.

• DCL: DCL is standing for data control language. It is used for controlling varieties access of multiple users inside one of the database by using some of the key SQL queries like REVOKE or GRANT.

• DML: DML stands for data manipulation language, it has been used for manipulating data available in one single database by using some key SQL queries INSERT or DELETE. Others set of SQL queries can also be considered as DML like SELECT, DELETE, INSERT or UPDATE.

The transparent DBMS is a type of DBMS which keeps its physical structure hidden from users. Physical structure or physical storage structure implies the memory manager of the DBMS, and it describes how the data stored on disk.

A checkpoint is like a snapshot of the DBMS state. Using checkpoints, the DBMS can reduce the amount of work to be done during a restart in the event of subsequent crashes. Checkpoints are used for the recovery of the database after the system crash. Checkpoints are used in the log-based recovery system. When due to a system crash we need to restart the system then at that point we use checkpoints. So, we don't have to perform the transactions from the very starting.

The Checkpoint is a type of mechanism where all the previous logs are removed from the system and permanently stored in the storage disk.

There are two ways which can help the DBMS in recovering and maintaining the ACID properties, and they are- maintaining the log of each transaction and maintaining shadow pages. So, when it comes to the log-based recovery system, checkpoints come into existence. Checkpoints are those points to which the database engine can recover after a crash as a specified minimal point from where the transaction log record can be used to recover all the committed data up to the point of the crash.

This is the common DBMS Interview Questions asked in an interview. Several responsibilities normally need to follow by a DBMS tester in the current IT industry. Normalization is one of the key properties specifically for the relational database management system (RDBMS). It is one of the important processes for analyzing multiple relational schemas where they have some dependency based on their different functional point of view and have to maintain one primary key for defining some of the key properties. Properties are defining below:

• Concentrating on minimizing data redundancy as much as possible.

• Ensuring on minimize deleting, updating or inserting data anomalies.

Some of the critical advantages of using DBMS is explaining below:

• Redundancy management: DBMS is mainly using for support one of the key mechanism for controlling the redundancy of data inside one of the database by integrating the same into one specific single database. As data has been stored in one single database, so there was no chance of duplicity.

• Sharing of Data: It is possible in case of DBMS to share entire data with multiple users who belong to the different role which defines be the database administrator. It is possible to share the same database with multiple users.

• The facility of taken back up and recovery of data.

• Ensuring to maintain proper integrity constraint.

• Maintain full independence of multiple data.

• Easy accessibility

• Easy data extraction and data processing due to the use of queries

The database can be defined in varieties approach. In a simple way, we can say the database is mainly handling the collection of multiple types of data, storing the same in define organize way, give key facility for the user for retrieving the same smoothly. It also can able to manage proper accessing of a specific user on the data and ensuring uploading critical data in a proper manner.

DBMS is called a Database Management System. One of the key purposes of using the application system revolves with varieties of data available in the industry. This is one of the key systems which helps users for storing multiple kinds of data in a systematic way, define the characteristics of data, retrieve smoothly whenever require an update that specific data on that corresponding database properly.