POSTGRESQL

Database:

• A database is an organized collection of digital data stored in a computer system.
• It lets people and apps find, change, and save information fast.

use of database:

• speed
• safety

types of database:

Relational (SQL):

• Structured Query Language
• Stores data in tables with rows and columns, like a spreadsheet.
• Great for banking or user lists.
• Examples are MySQL and PostgreSQL and SQLite.

Non-Relational (NoSQL):

• not only sql
• Uses flexible formats like documents or key-values instead of rigid tables.
• Great for messy or fast-changing data.
• Examples are MongoDB and Firebase.

Cloud:

• Runs on cloud platforms, making it easy to scale up without local hardware.

Difference between sql and nosql

DBMS:

• A Database Management System (DBMS) is a software tool used to create, store, manage, and retrieve data in a database.
• It acts as a safe bridge between the user or application and the actual data, keeping everything organized, secure, and easy to access.

Key Functions of a DBMS:

• Data Storage
• CRUD Operations
• Security
• Multi-User Access
• Backup and Recovery

RDBMS:

• RDBMS stands for Relational Database Management System, a software program that stores data in structured, tabular formats of rows and columns using tables linked by keys.

Difference between dbms and rdbms:

PostgreSQL :

• PostgreSQL (often called Postgres) is a free, open-source relational database management system.
• It stores data in tables with rows and columns, uses the SQL language, and is famous for being very reliable, fast, and safe with data.

why postgresql?

• PostgreSQL is a top choice for developers because it is a free, open-source relational database that balances strict ACID compliance and data safety with extreme flexibility, powerful JSON support, and a vast ecosystem of extensions.

Key Features:

• Open Source
• ACID Compliant
• Flexible
• Extensible

ORDBMS :

• ORDBMS stands for Object-Relational Database Management System.
• It is a database system that mixes a standard relational database with object-oriented programming features.
• It lets you store data in normal tables while also supporting complex data types, classes, and inheritance.

Difference between postgresql and mysql:

SUDO:

• The term sudo is a command used in Linux, macOS, and other Unix-like operating systems.
• It stands for "superuser do" or "substitute user do".
• It lets an authorized user run a program with the security power of another user, usually the system administrator or root.

APT:

• APT (short for Advanced Package Tool) is the default command-line software management system used by Debian and its derivative Linux distributions, including Ubuntu, Linux Mint, and Pop!_OS.
• It acts like an "app store" for your terminal, allowing you to easily find, install, update, and delete software packages.

PostgreSQL Installation:

use this command

sudo apt install postgresql postgresql-contrib

to check the status of postgresql is active or not

sudo systemctl status postgresql

sudo -i -u postgres

this command used to run a specific command as the postgres user.

psql

psql is the terminal-based interactive command-line interface for PostgreSQL, allowing you to type, execute, and manage SQL queries and database structures directly.

to create a database

create database cinemas;

use this command to connect database with user

\c cinemas;

to know the version of postgreSQL using this command

select version();

postgresql 16.14

to create a table

create table movie
(
movie_name varchar(80),
release_date date,
ticket int
);

to insert values to a table

insert into movie values('jananayagan','2026-07-15', 120);

to insert a value based on columns name

insert into movie (release_date, movie_name, ticket) values ('2025-01-10','sirai', 120);

we can also insert values without some values

insert into movie(movie_name, ticket) values ('karuppu',120);

to read a table using this command

select * from movie;