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Kamaleshwar A
Kamaleshwar A

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Introduction to Database in PostgreSQL

#database #sql #ai #programming

In database there is SQL - Structured Query Language is standard programming language for connect with and manage the database management system.

  • Query data — retrieve specific information from a database (e.g., SELECT * FROM users)
  • Insert, update, delete data — modify records within tables
  • Define database structure — create or alter tables, set relationships between them
  • Control access — manage permissions for who can read or modify data

DBMS - DATABASE MANAGEMENT SYSTEM

A Database Management System (DBMS) is software used to manage data from a database. It acts as an interface between the database and end users or applications, ensuring data is consistently organized, easily accessible, and secure.

  • A database is a structured collection of data that is stored in an electronic device. The data can be text, video, image, or any other format.
  • A relational database stores data in the form of tables, and a NOSQL database stores data in the form of key-value pairs.
  • A DBMS is a software that allows to create, update, and retrieval of data in an organized way. It also provides security to the database.
  • Examples of relational DBMS are MySQL, Oracle, Microsoft SQL Server, PostgreSQL, and Snowflake.
  • Examples of NOSQL DBMS are MongoDB, Cassandra, DynamoDB, and Redis.

PostgreSQL

In first postgres name was ingres that is Interactive Graphic and Research. After that name is postgres.

I was learned about how to install in the linux terminal and used in terminal.

sudo apt install postgresql postgresql-contrib
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After installation open the terminal,

sudo -i -u postgres
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Here,
sudo - super user do or substitute user do
-i - start to login shell
-u - user
postgres - username.

Then put this command in your terminal

psql
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Then you have postgres shell to do practice SQL and administer the database with your terminal.

Table create:

cinemas=# create table students(stud_id int, stud_name varchar(20), course_name varchar(20));
CREATE TABLE
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Insert Values:

cinemas=# insert into students values(11, 'Vignesh', 'Java full stack'),(23, 'Kamalesh', 'Python full stack'),(15, 'Dhanush', 'Full stack'),(28, 'Madhan', 'Full stack');
INSERT 0 4

cinemas=# insert into students values(16, 'Vidhya', 'Java full stack'),(22, 'Karthick', 'Data analytics'),(24, 'Karthiga', 'Python full stack'),(32,'Saravanan', 'Mern full stack');
INSERT 0 4
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The above database are created for myself to practice and learn the SQL.

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