DBMS stands for Database Management System. It is a collection of application programs which allow the user to organize, restore and retrieve information about data efficiently and as effectively as possible. Some of the popular DBMS’s are MySql, Oracle, Sybase, etc.

Relational Database Management System(RDBMS) is based on a relational model of data that is stored in databases in separate tables and they are related to the use of a common column. Data can be accessed easily from the relational database using Structured Query Language (SQL).

The advantages of DBMS includes:
• Data is stored in a structured way and hence redundancy is controlled.
• Validates the data entered and provide restrictions on unauthorized access to the database.
• Provides backup and recovery of the data when required.
• It provides multiple user interfaces.

Duplication of data in the database is known as data redundancy. As a result of data redundancy, duplicated data is present at multiple locations, hence it leads to wastage of the storage space and the integrity of the database is destroyed.

There are 3 types of relationships in Database:
• One-to-one: One table has a relationship with another table having the similar kind of column. Each primary key relates to only one or no record in the related table.
• One-to-many: One table has a relationship with another table that has primary and foreign key relations. The primary key table contains only one record that relates to none, one or many records in the related table.
• Many-to-many: Each record in both the tables can relate to many numbers of records in another table.

Normalization is the process of removing redundant data from the database by splitting the table in a well-defined manner in order to maintain data integrity. This process saves much of the storage space.
De-normalization is the process of adding up redundant data on the table in order to speed up the complex queries and thus achieve better performance.

Different types of Normalization are:
• First Normal Form (1NF): A relation is said to be in 1NF only when all the entities of the table contain unique or atomic values.
• Second Normal Form (2NF): A relation is said to be in 2NF only if it is in 1NF and all the non-key attribute of the table is fully dependent on the primary key.
• Third Normal Form (3NF): A relation is said to be in 3NF only if it is in 2NF and every non-key attribute of the table is not transitively dependent on the primary key.

BCNF is the Boyce Code Normal form. It is the higher version of 3Nf which does not have any multiple overlapping candidate keys.

Structured Query language, SQL is an ANSI(American National Standard Institute) standard programming language that is designed specifically for storing and managing the data in the relational database management system (RDBMS) using all kinds of data operations.

SQL statements are basically divided into three categories, DDL, DML, and DCL.
They can be defined as:
• Data Definition Language (DDL) commands are used to define the structure that holds the data. These commands are auto-committed i.e. changes done by the DDL commands on the database are saved permanently.
• Data Manipulation Language (DML) commands are used to manipulate the data of the database. These commands are not auto-committed and can be rolled back.
• Data Control Language (DCL) commands are used to control the visibility of the data in the database like revoke access permission for using data in the database.

DML compiler translates DML statements in a query language into a low-level instruction and the generated instruction can be understood by Query Evaluation Engine.

DDL Interpreter interprets the DDL statements and records the generated statements in the table containing metadata.

Advantages of SQL are:
• Simple SQL queries can be used to retrieve a large amount of data from the database very quickly and efficiently.
• SQL is easy to learn and almost every DBMS supports SQL.
• It is easier to manage the database using SQL as no large amount of coding is required.

Data abstraction in DBMS is a process of hiding irrelevant details from users. Because database systems are made of complex data structures so, it makes accessible the user interaction with the database.
For example: We know that most of the users prefer those systems which have a simple GUI that means no complex processing. So, to keep the user tuned and for making the access to the data easy, it is necessary to do data abstraction. In addition to it, data abstraction divides the system in different layers to make the work specified and well defined.

Following are three levels of data abstraction:
• Physical level: It is the lowest level of abstraction. It describes how data are stored.
• Logical level: It is the next higher level of abstraction. It describes what data are stored in the database and what the relationship among those data is.
• View level: It is the highest level of data abstraction. It describes only part of the entire database.
For example- User interacts with the system using the GUI and fill the required details, but the user doesn't have any idea how the data is being used. So, the abstraction level is entirely high in VIEW LEVEL. Then, the next level is for PROGRAMMERS as in this level the fields and records are visible and the programmers have the knowledge of this layer. So, the level of abstraction here is a little low in VIEW LEVEL. And lastly, physical level in which storage blocks are described.

Relational Algebra is a Procedural Query Language which contains a set of operations that take one or two relations as input and produce a new relationship. Relational algebra is the basic set of operations for the relational model. The decisive point of relational algebra is that it is similar to the algebra which operates on the number.
There are few fundamental operations of relational algebra:
• select
• project
• set difference
• union
• rename, etc.

Relational Calculus is a Non-procedural Query Language which uses mathematical predicate calculus instead of algebra. Relational calculus doesn't work on mathematics fundamentals such as algebra, differential, integration, etc. That's why it is also known as predicate calculus.
There is two type of relational calculus:
• Tuple relational calculus
• Domain relational calculus

Once the DBMS informs the user that a transaction has completed successfully, its effect should persist even if the system crashes before all its changes are reflected on disk. This property is called durability. Durability ensures that once the transaction is committed into the database, it will be stored in the non-volatile memory and after that system failure cannot affect that data anymore.

Normalization is a process of analysing the given relation schemas according to their functional dependencies. It is used to minimize redundancy and also used to minimize insertion, deletion and update distractions. Normalization is considered as an essential process as it is used to avoid data redundancy, insertion anomaly, updation anomaly, deletion anomaly.
There most commonly used normal forms are:
• First Normal Form(1NF)
• Second Normal Form(2NF)
• Third Normal Form(3NF)
• Boyce & Codd Normal Form(BCNF)

With dynamic loading, a routine is not loaded until it is called. This method is especially useful when large amounts of code are needed in order to handle infrequently occurring cases such as error routines.

Group functions work on a set of rows and return a single result per group. The popularly used group functions are AVG, MAX, MIN, SUM, VARIANCE, COUNT

The difficulty of accessing data as the path may be broken or missing defines inconsistent dependency. Inconsistent dependency enables users to search for data in the wrong different table which afterward results in an error as an output.

Case manipulation functions convert existing data in the table to lower, upper or mixed case characters.

The MOD function returns the remainder in the division operation.

Data stored in stored procedures can be retrieved much faster than the data stored in the SQL database. Data can be precompiled and stored in stored procedures. This reduces the time gap between query and compiling as the data has been pre-compiled and stored in the procedure. Procedures may or may not return values.

The BCP (Bulk Copy) is a utility or a tool that exports/imports data from a table into a file and vice versa.

A non-correlated subquery is an independent query, and the output of the subquery is substituted in the main query.

Lock escalation is the process of converting row or page locks into table locks. It is an optimization technique used by RDBMS like SQL Server dynamically.

TRUNCATE removes all the rows from the table, and it cannot be rolled back.
DROP command removes a table from the database and operation cannot be rolled back.

A stored procedure which calls by itself until it reaches some boundary condition. This recursive function or procedure helps programmers to use the same set of code any number of times.

Collation is defined as set of rules that determine how character data can be sorted and compared. This can be used to compare A and, other language characters and also depends on the width of the characters.

Datawarehouse is a central repository of data from multiple sources of information. Those data are consolidated, transformed and made available for the mining and online processing. Warehouse data have a subset of data called Data Marts.

Auto increment keyword allows the user to create a unique number to be generated when a new record is inserted into the table. AUTO INCREMENT keyword can be used in Oracle and IDENTITY keyword can be used in SQL SERVER.

A DB trigger is a code or programs that automatically execute with response to some event on a table or view in a database. Mainly, trigger helps to maintain the integrity of the database.

Black Box Testing is a software testing approach that involves testing the functions of software applications without knowing the internal code structure, implementation details, or internal routes. Black Box Testing is a type of software testing that focuses on the input and output of software applications and is totally driven by software requirements and specifications. Behavioral testing is another name for it.

A self-join is a type of join that can be used to connect two tables. As a result, it is a unary relationship. Each row of the table is attached to itself and all other rows of the same table in a self-join. As a result, a self-join is mostly used to combine and compare rows from the same database table.

The UNIQUE Constraint prevents identical values in a column from appearing in two records. The UNIQUE constraint guarantees that every value in a column is unique.

OLTP, or online transactional processing, allows huge groups of people to execute massive amounts of database transactions in real time, usually via the internet. A database transaction occurs when data in a database is changed, inserted, deleted, or queried.

A SELECT command gets zero or more rows from one or more database tables or views. The most frequent data manipulation language (DML) command is SELECT in most applications. SELECT queries define a result set, but not how to calculate it, because SQL is a declarative programming language.

A stored procedure calling itself until it reaches some boundary condition is a recursive stored procedure. It enables the programmers to use a set of code any number of times.