Answer:- The Hummingbird update is a Google Search algorithm that was introduced in 2013 to make searches more about context and less about keywords. Google now better understands the intent of the keywords used than just the keywords.

Answer:- The Mobilegeddon update focuses on the mobile-friendliness of a website for better SERP ranking as the number of people using Google on mobile devices has increased significantly over the years.

Answer:- The Google Pigeon update was introduced in 2014 to provide preference to local search results (location and distance are the key aspects of the search strategy here).

Answer:- A database is an organized collection of structured data that can be stored, easily accessed, managed, and retrieved digitally from a remote or local computer system. Databases can be complex and vast and are built with a fixed design and modeling approach. While smaller databases can be stored on a file system, large ones are hosted on computer clusters or cloud storage.

Answer:- A database is an organized collection of structured data that can be stored, easily accessed, managed, and retrieved digitally from a remote or local computer system. Databases can be complex and vast and are built with a fixed design and modeling approach. While smaller databases can be stored on a file system, large ones are hosted on computer clusters or cloud storage.

Answer:- A database management system or DBMS is system software that can create, retrieve, update, and manage a database. It ensures the consistency of data and sees to it that it is organized and easily accessible by acting as an interface between the database and its end-users or application software. DBMS can be classified into four types: • Hierarchical Database: It has a treelike structure with the data being stored in a hierarchical format. The parent in a database can have multiple children, but a child can have only a single parent. • Network Database: This type of database is presented as a graph that can have many-to-many relationships allowing children to have multiple children. • Relational Database: It is the most widely used and easy-to-use database. It is represented as a table and the values in the columns and rows are related to each other. • Object-oriented Database: The data values and operations are stored as objects in this type of database, and these objects have multiple relationships among them. RDBMS stores data in the form of a collection of tables. The relations are defined between the common fields of these tables. MS SQL Server, MySQL, IBM DB2, Oracle, and Amazon Redshift are all based on RDBMS.

Answer:- SQL stands for Structured Query Language. It is the standard language for RDBMS and is useful in handling organized data that has entities or variables with relations between them. SQL is used for communicating with databases. According to ANSI, SQL is used for maintaining RDBMS and for performing different operations of data manipulation on different types of data by using the features of SQL. Basically, it is a database language that is used for the creation and deletion of databases. It can also be used, among other things, to fetch and modify the rows of a table.

Answer:- Normalization is used in reducing data redundancy and dependency by organizing fields and tables in databases. It involves constructing tables and setting up relationships between those tables according to certain rules. The redundancy and inconsistent dependency can be removed using these rules to make normalization more flexible. The different forms of normalization are: • First Normal Form: If every attribute in a relation is single-valued, then it is in the first normal form. If it contains a composite or multi-valued attribute, then it is in violation of the first normal form. • Second Normal Form: A relation is said to be in the second normal form if it has met the conditions for the first normal form and does not have any partial dependency, i.e., it does not have a non-prime attribute that relies on any proper subset of any candidate key of the table. Often, the solution to this problem is specifying a single-column primary key. • Third Normal Form: A relation is in the third normal form when it meets the conditions for the second normal form and there is not any transitive dependency between the non-prime attributes, i.e., all the non-prime attributes are decided only by the candidate keys of the relation and not by other non-prime attributes. • Boyce-Codd Normal Form: A relation is in the Boyce-Codd normal form or BCNF if it meets the conditions of the third normal form, and for every functional dependency, the left-hand side is a super key. A relation is in BCNF if and only if X is a super key for every nontrivial functional dependency in form X –> Y.

Answer:- Denormalization is the opposite of normalization; redundant data is added to speed up complex queries that have multiple tables that need to be joined. Optimization of the read performance of a database is attempted by adding or grouping redundant copies of data.

Answer:- Join in SQL is used to combine rows from two or more tables based on a related column between them. There are various types of Joins that can be used to retrieve data, and it depends on the relationship between tables. There are four types of Joins: • Inner Join • Left Join • Right Join • Full Join

Answer:- There are four different types of SQL Joins: • (Inner) Join: It is used to retrieve the records that have matching values in both the tables that are involved in the join. Inner Join is mostly used to join queries. • Left (Outer) Join: Use of left join is to retrieve all the records or rows from the left and the matched ones from the right. • Right (Outer) Join: Use of Right join is to retrieve all the records or rows from the right and the matched ones from the left. • Full (Outer) Join: The use of Full join is to retrieve the records that have a match either in the left table or the right table.

Answer:- SQL queries are divided into four main categories: • Data Definition Language (DDL) DDL queries are made up of SQL commands that can be used to define the structure of the database and modify it. • CREATE Creates databases, tables, schema, etc. • DROP: Drops tables and other database objects • DROP COLUMN: Drops a column from any table structure • ALTER: Alters the definition of database objects • TRUNCATE: Removes tables, views, procedures, and other database objects • ADD COLUMN: Adds any column to the table schema • Data Manipulation Language (DML) These SQL queries are used to manipulate data in a database. • SELECT INTO: Selects data from one table and inserts it into another • INSERT: Inserts data or records into a table • UPDATE: Updates the value of any record in the database • DELETE: Deletes records from a table • Data Control Language (DCL) These SQL queries manage the access rights and permission control of the database. • GRANT: Grants access rights to database objects • REVOKE: Withdraws permission from database objects • Transaction Control Language (TCL) TCL is a set of commands that essentially manages the transactions in a database and the changes made by the DML statements. TCL allows statements to be grouped together into logical transactions. • COMMIT: Commits an irreversible transaction, i.e., the previous image of the database prior to the transaction cannot be retrieved • ROLLBACK: Reverts the steps in a transaction in case of an error • SAVEPOINT: Sets a savepoint in the transaction to which rollback can be executed • SET TRANSACTION: Sets the characteristics of the transaction

Answer:- The major applications of SQL include: • Writing data integration scripts • Setting and running analytical queries • Retrieving subsets of information within a database for analytics applications and transaction processing • Adding, updating, and deleting rows and columns of data in a database

Answer:- Constraints in SQL are used to specify some sort of rules for processing data and limiting the type of data that can go into a table. Now, let us understand what is a default constraint. A default constraint is used to define a default value for a column so that it is added to all new records if no other value is specified. For example, if we assign a default constraint for the E_salary column in the following table and set the default value to 85000, then all the entries of this column will have the default value of 85000, unless no other value has been assigned during the insertion.