Lecture 5

Question 1

What is a databas

Answer 1

A database is an organized collection of structured information, or data, typically stored electronically in a computer system.

Question 2

Example of SQL databse

Answer 2

MySQL,
PostgreSQL,
Oracle,
MS-SQL Server

Question 3

Example of NoSQL database

Answer 3

MongoDB,
GraphQL,
HBase,
Neo4j,
Cassandra

Question 4

What is database normalization

Answer 4

Normalization is a database design technique that reduces data redundancy and eliminates undesirable characteristics like Insertion, Update and Deletion Anomalies.

Normalization rules divides larger tables into smaller tables and links them using relationships.

Question 5

What is SQL

Answer 5

Structured Query langauge is a programming language used by nearly all relational databases to query, manipulate, and define data, and to provide access control.

Question 6

Describe DDL

Answer 6

DDL stands for Data Definition Language. The DDL commands help to define the structure of the databases or schema.

Question 7

Mention some commands

Answer 7

CREATE: It is used to create a new database and its objects such as table, views, function, stored procedure, triggers, etc.
DROP: It is used to delete the database and its objects, including structures, from the server permanently.
ALTER: It’s used to update the database structure by modifying the characteristics of an existing attribute or adding new attributes.
RENAME: This command renames the content in the database.

Question 8

Syntax to create a database

Answer 8

CREATEDATABASEdatabasename;

CREATE DATABASE pauCafe;

Question 9

Syntax to drop database

Answer 9

DROP DATABASE databasename;

DROP DATABASE pauCafe;

Question 10

Syntax to drop table

Answer 10

DROP TABLE table_name;

Question 11

Synxtax to alter table

Answer 11

ALTER TABLE Students
ADD Email varchar(255);

Question 12

Syntax to rename statement

Answer 12

ALTER TABLE table_name
RENAME TO new_table_name;

Question 13

Describe DML

Answer 13

Data Manipulation Language. The DML commands deal with the manipulation of existing records of a database.

Question 14

Mention some DML commmands

Answer 14

SELECT: This command is used to extract information from a table.
INSERT: It is a SQL query that allows us to add data into a table’s row.
UPDATE: This command is used to alter or modify the contents of a table.
DELETE: This command is used to delete records from a database table, either individually or in groups.

Question 15

Syntax for select comand

Answer 15

SELECT column1, column2, …
FROM table_name;

Question 16

Syntax for where command

Answer 16

WHERE Syntax
SELECT column1, column2, …
FROM table_name
WHERE condition;

Question 17

Syntax for update command

Answer 17

UPDATE Syntax
UPDATE table_name
SET column1 = value1, column2 = value2, …
WHERE condition;