DEV Community: boopalan

Power of open source

boopalan — Wed, 02 Sep 2026 04:37:59 +0000

Open design was popular in the week, so i am curies to check what it has inside, when i check to download it for Ubuntu, there is no app for linux in there official page, however it is an open source so i am checked it source code and they give the project in the .zip

so i am download it and build it and it work well in the local host

practicing joins in PostgreSQL

boopalan — Wed, 02 Sep 2026 04:33:28 +0000

Altering table columns

boopalan — Sat, 29 Aug 2026 12:02:19 +0000

alter is the keyword allow us to make changes in the table structures and database

we can rename tables, make changes in the columns names, inserting new columns, removing existing columns for all those activites alter keywords will allow us to do it.

let see how to do rename a column

to see tables in our connect database we can see \dl

\dt

here we can see that there is only one table in this database, that is employee

create table dummytable(id int);

\dt

now we see that we have two tables, that are dummytable and employee

let we see how to rename a table

alter is the keyword to indicate we are actually going to change something and we want to specify what we are actually going to change by using the alter keyword whether we are changing the table or database.

After if we specify table this query will going to work for the table, other wise it we specify table it will work for the table

finally we want say for which table we are going to this work by name of the table, here we will do for the dummytable

the rename keyword explicity specifies our table activity is rename activity and at last we want to give the new name of the table using the to keyword

alter table dummytable rename to tabledummy;

now check our table does the name was changed or not

this time the dummytable is changed into tabledummy

it shows error for doing same thing for again

adding new columns

for now we have only one column and it's type is intger

let see how to add new column

after specifying the table designigation we want to say which changes we are going to do, if we want to add new columns we want say that ADD COLUMN and new column name and its type

alter table tabledummy add column name varchar(20);

here we are specifying the our new column name is as name and it type as varchar with limit 20

to see the changes in the tabledummy

note only one columns we can add more then one column at the same type

alter table tabledummy 
add column age smallint
add column city varchar(20)
add column phone bigint;

NOTE do not forget to sperate the each columns by comma

alter table tabledummy 
add column age smallint,
add column city varchar(20),
add column phone bigint;

to check the alters

for saft querying we can use the IF NOT EXISTS

ALTER TABLE tabledummy
ADD COLUMN IF NOT EXISTS age smallint;

ALTER TABLE tabledummy
ADD COLUMN IF NOT EXISTS age smallint,
ADD COLUMN IF NOT EXISTS city varchar(20);

ALTER TABLE tabledummy
ADD COLUMN IF NOT EXISTS age smallint,
ADD COLUMN IF NOT EXISTS city varchar(20),
ADD COLUMN IF NOT EXISTS email varchar(20);

remove a columns

in new column inserting query if we replace add as drop it will work as the drop query, do not forget that we do not need the data type for the removing the columns

alter table tabledummy 
drop column city,
drop column phone;

just like safe column inserting we can perfor the safe removing the column

\d tabledummy

alter table tabledummy 
drop column if exists age;

alter table tabledummy 
drop column if exists name;
drop column if exists age;
drop column if exists email;

\d tabledummy

also we can conver the type of the table column to another type we will see about it later

inserting records in the database, and querying them

boopalan — Mon, 24 Aug 2026 16:28:37 +0000

creating complex tables having many columns inside a database and working some of the basic operations on them

let we see step by step

1) creating database

create database company

2) connect with database

\c company

3) creating tables

Note do not forget to differentiate each columns by by comma,

create table employee(
empid integer, 
name varchar(25), 
designation varchar(25)
dept varchar(25), 
salary integer);

create table employee(
empid integer, 
name varchar(25), 
designation varchar(25), 
dept varchar(25), 
salary integer);

Now, we are going to see more in-depth interactivity with table columns

to insert values in the table first we use the keyword insert, it will trigeres we are going to insert some thing in the table and then we want to define the desigination where we are going to insert values, here we created a employee table for practice, into employee but until now we yet not define what values we are actually going insert in the desigination, so for values we want to give them inside () for each colmuns, here (123, 'Kavin', 'Software Engineer','DB',25000)
are the values for respective columns we want to insert them.

insert into employee values(123, 'Kavin', 'Software Engineer','DB',25000);

insert into employee values(124, 'Viyan', 'Software Engineer', 'AI',27000);

to verifiy our values are inserted or not in the employee table

select * form employee

NOTE: some of mistakes from not form

select * form employee

also it give hint to where we are going our mistakes

up to now we are actually insert only one values
suppose if we want to insert multiple values means how can we able to do it?
first can we able to do it?, yes postgres database allow as to do it

it is not complex just query we just want to contineouly insert them after one another with comma seperation

this is the example query to insert multiple values in the employee table

insert into employee values(101, 'Arul', 'Team Lead', 'Front End', 35000), (101, 'Agaran', 'Team Lead', 'DB', 45000);

here we are define more then one row in a single query, after the values keywords if we use define several values seperated by the , it will all takes as the next next rows.

insert into employee values(202, 'Arul', 'Team Lead', 'Front End', 35000), values(401, 'Agaran', 'Team Lead', 'DB', 45000);

if we use values for all the records it will lead us to happening error

To verify our multiple values inerstion

select * from employee

it gives us all the values we inserted the employee table

selecting some columns form the table

to select only specific column we do not want to use * it will lead us to get all the values form our table instead if we specify only columns what we want

for example to get only the name column values

select name from employee

to get more then one columns name, designation

select name, designation from employee

try out with different column names

select name, dept form employee

suppose if we want get distint values form a columns means how to get it, for getting distinct values from a columns we can use the distinct keyword before the columns name

select distinct dept from employee;

the distinct keyword will help to select distinct unique values form the table

select distinct designation from employee;

select distinct dept, designation from employee;

where clause

we want to select a name with some conditions means how to do it ?

using postgres can we able to select a name with some conditions, yes for doing this is where where clause came and helps to selection with specific conditions

it helps to filter the quering the values with more then one conditions

select * from employee where dept = 'DB';

it will select those who all are having the values DB at the dept columns

trying some more with different coditions

select * from employee where designation = 'Team Lead';

suppose of we want to count the queirng result can we able to do it?
Yes for counting the queries we can use count

select count(*) from employee where dept = 'Team Lead';

count(*) is a function it will count the result results and returen the the count value in the name of the count column

select count(*) from employee where dept = 'DB';

AND

adding more conditions

using and keyword

select * from employee where dept ='DEV' and designation = 'Manager';

select name from employee where dept = 'Front End' and designation = 'Team Lead';

select * from employee where dept ='AI' and designation = 'Software Engineer';

using `or` keyword

select * from employee where dept = 'DB' or designation = 'Team Lead';

select * from employee where dept = '' or designation = '';

alias

suppose if you want to rename the quering column name, we can do it by using the as

select dept from employee;

here we are getting the actual column name in the database

suppose if we want to rename it form dept to Department is it possible ?
yes but one thing is postgres is non case sensitive so it will conside all of the upper cases into lower cases

select dept as  Department from employee;

select dept as  DEPARTMENT from employee;

now the dept is renames as the department or DEPARTMENT even though if we given in letter with upper cases it converts all of them into lower cases

we can see that in the result the Department and DEPARTMENT is converted into lower case `department

can we use this more then one column

in this way can we able to rename more then one one columns
yes, let we see that

`sql select name as empname, dept as Department from employee; `

Not equals to:

!= , <> , not are used for the not equals

`sql select * from employee where dept <> 'DB'; `

`sql select * from employee where dept != 'DB'; `

`sql select * from employee where not dept = 'DB'; `

we can able to see for all this != , <> , not are giving the same result

`sql select * from employee where not dept <> 'DB'; `

between

`sql select * from employee where salary between 19000 and 35000; `

does this means can we only able to use it only for the integer ranges?
What are the other data types we can be able to use between ?

`sql select * from employee where not salary between 19000 and 35000; `

can we between is only works for numeric values or can we ablet to do it other data types. postgres allow user to use for the char, text, data and more types

for example let we see how to use it for varchar type

`sql select name from employee where name between 'A' and 'K'; `

`sql0 select name from employee where name between 'a' and 'k'; `

it does not care about lower cases

using `in`

`sql select * from employee where dept = 'DB' or dept = 'AI'; `

`sql select * from employee where dept = 'DB' or dept = 'Front End' or dept = 'AI'; `

instead of using check the value one by one can use to check the value in a range of items

`sql select * from employee where dept in ( 'DB', 'Front End' , 'AI'); `

`sql select * from employee where dept in ('Front End' , 'AI'); `

`sql select * from employee where dept not in ( 'DB', 'Front End' ); `

what will happen if we change the not in to in not

`sql select * from employee where dept in not( 'DB', 'Front End' , 'AI'); `

order by

i we want to sort the value in a specify core we can use the order by
it will work for almost all types in the postgres

`sql select * from employee order by dept `

here it automatically identify the type of the dept column and sort it by alphabe wise

`sql select * from employee order by empid `

at this time it sort the empid by assending order

`sql select * from employee order by salary `

`sql select * from employee order by name `

similarly for the salary and name columns

Can we able to do order by multiple columns, yes

`sql select * from employee order by name, salary; `

`sql select * from employee order by name, dept; `

it will first select the column by and then it will order the second column by having the same values

what is the default order by ?

Suppose if we want to order decenting means how can I able to do it?
for doing the decenting order can use the desc

`sql select * from employee order by salary desc; `

let we do how to do one ascending and descenting order

`sql select * from employee order by salary desc, dept asc; `

what is the differences between the both queries

`sql select * from employee order by salary asc, dept desc; `

`sql select * from employee order by dept asc, salary desc; `

limit

`sql select * from employee order by salary limit 3; `

it will give the first three;

incase if we want the last three means how can we able to do it

`sql select * from employee order by salary desc limit 3; `

like

`sql select * from employee where name like 'a%'; `

'a%' will select name that stating with letter a
'%a' will select name that ending with letter a

for select the name a in between the words

`sql select * from employee where name like '%n'; `

`sql select * from employee where name like '%l'; `

`sql select * from employee where name like '%a%'; `

`sql select * from employee where name like '%a%a%'; `

suppose if I want to select the number, data and can I use the regex ?

postgress basics

boopalan — Sun, 23 Aug 2026 16:41:44 +0000

Today without any decent knowledge in database we cannot
step in/completer even a small mini progjects, so companies will expcet
more deeper knowlege in the database.
The story of the database begin from the Telephone directory,

Telephone directory

In early day to get some ones phone number we use telephone directory, it helps to find out a right one's number what we want's form the thousands of numberes, We can idendify number by name, location and with some more additional informations for out actual requirement.

Yellow pages

It is helps for to get the business peoples numberes, finding some one's number for our requirements from thousands of numbere is not easy task, we do not who was doing which kind of work/business, instead of searching the business requirement from the whole telephone directory, we can get the required business numbers from the yellow pages directly, it act as a business advardiesment for the business peopels

one of the common thing from this two ways are saving the data in the method of rows and columns.

Arrival of personal computers

After the development of personal computers, we can able to see the many producets rais to saving data in our personal computers, from those all products Microsoft excel sheet is one of them. Microsoft excel is the one of the extended version of this feature for personal computer to saving data in row and columns order, micorsoft access is specifically designed for using it as an database.

excel rapidly developed with many features like spreadsheets, formulas, graphs and many more features but on the other hand micorsoft access is developed only for saving and retriving the data faster. it focus the speed and reliability and additional features for the business data storage management systems or it is commonly called as database management systems.

throughout this DBMS we can save data in multiple tables, tables and sheets are nearly look like similar maner, for the business requirement we can create a individual and multiple tables for saving the data, instead of saving the whole data in a complex single sheet.

Even though we have use multiple tables, we unable to resolve the relations between the multiple tables, to solve this issue later they move on the RDBMS. it resolve the issue of connecting multiple tables in a single database.

By using the RDBMS we can connect multiple tables, through out this method we can establish the relation ship between the more then one table, helps to track and resolve the business dependencies eventhoug in the complex table structure.

nowadays for development we mostly use the RDBMS.

Some of the RDBMS database are SQLite, MYSQL, Oracle Database and more.

What is SQL?

SQL (Structured Query Language) is a standardized programming language used to manage and manipulate relational databases.

It serves as the universal language for communicating with databases, allowing users to:

Query data (retrieve specific information)
Insert, update, and delete records
Create and modify database structures (tables, schemas)

SQL acts as a bridge between users/applications and the database management system (DBMS).

Most major database systems support SQL — including MySQL, PostgreSQL, Oracle, SQLite, etc., each databases may have slight variations.

NOTE: SQL is not the database itself — it's the language used to interact with it

Where we can use the SQLite?

it is serverless and no configuration needed database.
It is light weight and super fast database, we can choose it for the smaller application, most of the android's offline first apps are uses the SQLite database locally.
Perfect when we need a reliable, local, single-user or for small-team database management.

what is NOSQL?

it does not use the SQL, it does not store the data in the rows and colums structured formate, it save the data in the key value pair or in the JSON formate. It is flexible or schema-less
scalable alternative to relational databases

It sacrifices some consistency and complex querying ability in exchange for speed and flexibility.

Some of the examples for the NOSQL's are MongoDB, Apache Cassendra, Redis, Neo4j and more

which database we choose in here to study?

A single databsase cannot be solutions for all the poblems

Based one the busines requirement we choose the databases.
For example bancking and financial service are mostly depends on the the SQL. social medias, Iot services, real-time analytices are mostly like to the NOSQL.

At a fresher here we are going to choose which DB to study, here I am going to study the Postgresql, because it has several advances comparing to the other sql databases.
later we can be able to easily pick NOSQL and most of the other sql database will have similar concepts may little variations but it does not lead us to study from scratch.

what is PostgreSQL?

PostgreSQL is an open-source and Advance Object-Relational DataBase Management System(ORDBMS), it has excellent SQL standard and best fo the complex queries and more.

History

in the early development Postgresql is called in name of INteractive GRaphics and REsearch. Later they improved it to the next stage with many features and they called it and the POSTGRESQL.

what is the differrence between the Postgres and other databases

what is the differences betweent the ORDBMS and RDBMS

Features	ORDBMS	RDBMS
Core Concept	Stores data in flat, two-dimensional tables of rows and columns.	Stores data in tables, but also allows objects, classes, and inheritance.
Data Types	Limited to basic types: Numbers, Text (Strings), Dates, and Booleans.	Allows User-Defined Types (UDTs) and complex objects
Inheritance	Not supported.	Supports table and type inheritance (like OOP languages)
Data Integrity	Relies on Primary Keys and Foreign Keys to link tables.	Uses keys, but can also use pointers/references (like Object IDs) to link rows, similar to object-oriented programming.
Complex Data	Hard to store complex data (like images, audio, or a whole "Customer Profile"). It is usually stored as a BLOB (Binary Large Object) outside the logic of the DB.	Can store complex data natively. You can create a custom Customer_Type that includes their name, photo, and address as a single unit.
Functions & Behavior	Data is "dumb." It only holds values. Logic lives in the application (e.g., Python or Java code).	Supported. You can create a Person type, and then create a Student type that inherits Person's traits but adds a "Major".

Differences between the PostgreSQl and MySQL

Feature	MySQL	PostgreSQL
Best Known For	Speed, reliability, and ease of use for standard web apps.	Advanced features, complex queries, and data integrity.
Database Type	Primarily a traditional RDBMS, but getting more object features.	A true ORDBMS (Object-Relational Database).
Open Source License	Owned by Oracle. Uses GPL (General Public License) with commercial licenses available.	Completely free and open-source. Uses a very permissive PostgreSQL License (similar to MIT/BSD).
Complex Queries	Good for simple SELECT, INSERT, UPDATE, DELETE statements.	Superior for highly complex analytical queries, window functions, and Common Table Expressions (CTEs).
Data Integrity	Historically allowed "sloppy" data (e.g., truncating text or accepting invalid dates) unless strict mode is enabled.	Extremely strict. It will reject any invalid data to protect your database at all costs.
JSON Support	Stores JSON as a string. You can search it, but it is not highly optimized.	Treats JSON as a first-class citizen. You can index JSON data and query it incredibly fast (often used as a NoSQL alternative).
Speed	Extremely fast for heavy read-only operations (SELECT queries).	Extremely fast for heavy write operations, massive datasets, and complex joins.
Case Sensitivity	Table names are tied to the operating system. On Linux, Users and users are different tables.	Not case-sensitive for table names. Users and users are treated as the same thing (unless quoted).

why PostgreSQL is call ORDBMS?

PostgreSQL is called an Object-Relational Database Management System (ORDBMS) because it combines the classic features of a Relational Database (tables, rows, SQL, and relationships) with Object-Oriented Programming concepts (custom data types, objects, and methods/functions).

In the computer programming world (specifically Object-Oriented Programming, or OOP), an "object" is a single unit that bundles together Data (Properties) and Behavior (Methods/Actions).

Custom Data Types
Inheritance (Parent and Child Tables)
Methods / Stored Procedures

Installation

sudo apt update

it helps to fix the dependenies issues,

sudo apt install postgresql postgresql-contrib

it will install the postgresql database

sudo systemctl status postgresql

to startup on the booting postgresql

sudo systemctl enable postgresql

it will help to enable the postgresql always startup when the computer boots

Who can use Postgres database

sudo -i -u postgres

sudo : is helps we are give the permission for this software as the super user for doing things
-i : is the start a login shell [ Loading the User's Environment automatically ]
-u : is now act as the user

postgres : here postgres is the by default admin user for the postgresql database

here up to now we are just login as in the name of the postgres user name not yet in the database just we are switch by default user to the postgres user

suppose if we want go back we can simple enter the exit for postgres user to the normal user again

NOTE: here anyone can use the postgres database but at now or at the installation we have to use it in the default postgres user

how to use postgres

now we are actually going inside or connecting in to the postgresql database, if we give the psql

normally we can do similar kind of thing like whenever if the give the python in the terminal it will opens the python interpreter

for the security reasons by default other then postgres user database does not allows any one to login in the database.

NOTE: can we change or add another user to login in the database

What is the psql ?

psql is the interactive command-line client for the PostgreSQL server,

some of the helping commands

\h - help

\l - list

\r - stop | recover suppose if we entered an wrong command

name of the database

Owner who is the owner of the database

to quit for the \l
esc → :q

to get all the databases form the postgress ?

\l

here we can ablet to see list of items in the name columns? this all are the default databases in the postgress

we will see about it later in this discussion

how to create a database ?

create database database;

it is insencitieve

CREATE DATABASE DADABASE;

NOTE: whenever if we create or execute a command or query in the database
when have to use ; to define the commend is ending at that point.

CREATE DATABASE movies;

we can able to see all the database name;

suppose or in by mistake if you create a database with wrong name how you will delete the database

DROP DATABASE movies;

finally the database was deleted or removed from out databases

NOTE : it is not recomenede way to remove the do it

How to connect our database?

\C DADABASENAME

\c databasename

it will connect to that particular database what we are looking to connect
when we given as the databasename

To see the version ?

do you think databases have version, just like version in software postgress also have versions, knowing version is importent to moving the development project to the production stage.

to get version of the postgress, we can use

select version();

to esc form version

esc :q

Getting current date using postgress

select curent_data;

it will get the current date for this query

to create a table in the database

what is the minimum requirement to create or ensure it is a table ?

In terms of table prespective, how we can ensure that what we are going to store in the table, for table we are creating it to save some kind of data, without need of saving date we do not need to creating table.

suppose if we try to create a table without defining the
any columns what will happen

DB=# create table TABLE
DB-#

when we just give this line create table TABLE
without semi-colon

you can able to see that in the next line equal(=) sign changes into minus(-),

what was happening in the next line, was - indicate that postgress was actually waiting for your next command for what you will going to given as the next inputs, it will wait for until we ending the line using ;

to end the session just we can simple given the ;

DB=# create table TABLE
DB-#;
SOME ERROR
DB=#

now, you can see an error with invalid sql error

what will be happen if we try to connect a database that does not exists?

\c collagexyz;

to connect to the table we created

be sure database was actually created before

\c collage;

so postgress expect to user to create a at least one column in the table.

we want to define the value type in the columns it will helps to process the data faster and quiceker,
for a business perspective we can not compliment anything in the perforamnce

create table movie(id int);

Types in PostgreSQL

s.no	TYPE	usage
1	CHAR(n)	Fixed length text, having limit upto `n`
2	VARCHAR(n)	variable length with n limit
3	TEXT	Unlimited variable length
4	CHAR (without length)	it will allow as to store only one letter

s.no	TYPE	usage
1	SMALLINT	small whole numbers ( -32,768 to 32,767 ), we can use it for storing age, and small counts
2	INTEGER	it allow as to store store values in between -2 to 2 billion
3	BIGINT	some time integers requires to store more then billion values, in swituations like storing population exeds the count.
4	DECIMAL(p ,s)	some times values need to store in the decimal points
5	NUMERIC(p ,s)	it is similar to the DECIMAL
6	REAL	Scientific measurements needs Approximate numbers.
7	DOUBLE PRECISION	- Scientific calculations
8	SERIAL	Auto-incrementing integer
9	BIGSERIAL	Auto-incrementing big integer

s.no	TYPE	formate
1	DATE	`YYYY-MM-DD`
1	TIME	`HH:MM:SS`
1	TIMESTAMP	`YYYY-MM-DD HH:MM:SS`
1	TIMESTAMPTZ	`YYYY-MM-DD HH:MM:SS TZ`
1	INTERVAL	`1 year 2 months`
1	TIME WITH TZ	`HH:MM:SS TZ`

BOOLEAN - instead of saving the TRUE, FALSE we can also use as a values NULL

JSON - JSON data

JSONB - Binary JSON

s.no	Type	usage	formate
1	INET	IP address	`192.168.1.1`
2	INET	IP network	`192.168.1.0/24`
3	MACADDR	MAC address	`08:00:2b:01:02:03`
4	POINT	2D point	`(x,y)`
5	CIRCLE	Circle	`<(x,y),r>`
6	BOX	Rectangle	`(x1,y1),(x2,y2)`

anytype[] - Array of typed values

ENUM - helps to store string options in the column
('pending', 'processing', 'shipped', 'delivered')

MONEY - Currency amount

Let we see how to create table inside

can we create tables directly in the postgress ?

just now we saw how to create databases in the postgress but can we create tables in the
postgress, not the strecture of the tables we can only create tables inside database

suppose if we create tables without entering any database, it will show error

ensure that you are inside the database!

movies=#

now we can see that postgres=# is changed movies=#

this indicates we are inside the movies tables

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

things we do not want to

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

movie is the name of the table

create table movie here we are going to create a
table using the table keywords

and here we naming table as movie

movie_name, release_data, ticket
this all are the name of the columns and
we define the the value type of the columns

varchar is define we are actually going use string
value is a type for the movie_name column,
as well as we define the colmn type respectively for the release_date, ticket as the type of date and int

suppose if we try to create a table without defining the any columns what will happen

SELECT current_database();

Insert data into the tables

insert into movie values ('syperman', '2021-07-15', '120');

inseting more datas

insert into movie values ('superman', '2022-05-02', '120');

insert into movie values ('flash', '2022-05-02', '120');

here we are actually inserted data in a particular order, what will
happen if we inserted in a wrong formate ?

Suppose if we want to customize the data means how to it?

What will happen if we does not give any one value for this column

can we change the order of the insertion values

insert into movie (release_date, movie_name, ticket) values ( '2024-01-11', 'batman', 120);

insert into movie values ('superman', '2022-05-02', '120');

this type of inerstion is positional arguments

insert into movie (release_date, movie_name, ticket) values ( '2024-01-11', 'batman', 120);

then what is name of this type of insertion

how to select the values for the database tables

getting the values in the tables

* is the universal selector it will get all the values in the table

select * from movie;

while quering the data incase you are typed wrongly column name to correcting if you get some help form prostgres we can do it easily to given an hand for the write the columns name we can use \d details of the table

\d TABLENAME

\d movie

select release_data, movie_name, ticket from movie;

both methods are equal
at first attempt we are using universal selector *, at second attempt we are get the value of each by using it's column name

suppose if we do not want any columns we can skip it

select release_data, movie_name from movie;

select movie_name, ticket from movie;

select  ticket from movie;

Interview questions to revision

1) what is postgreSQL?
2) DBMS vs RDBMS ?
3) SQL vs NOSQL ?
5) how do you find PostgreSQL version,
6) how to create Database ?
7) how to create Tables ?
8) PostgreSQL vd MySQL ?
9) what is sudo?
10) What is apt ?
11) Why PostgreSQL is ORDBMS ?

july 30

boopalan — Thu, 30 Jul 2026 14:54:44 +0000

trying the FFI between the c and the python3

i am planning the do a very simple ffi for an simple c program

int add (int a, int b) {
   return a + b;
}

now let we compile this simple program for the linux

gcc -shared -o libadd.so add.c

using this.so file in python program


import ctypes
import os

if os.name == 'posix':  
    lib = ctypes.CDLL('./libadd.so')
else:  
    lib = ctypes.CDLL('./add.dll')

lib.add.argtypes = [ctypes.c_int, ctypes.c_int]  
lib.add.restype = ctypes.c_int              

result = lib.add(5, 7)
print(f"5 + 7 = {result}")

July 13 blog

boopalan — Sun, 19 Jul 2026 12:43:40 +0000

what is signals in Angular?

https://angular.dev/guide/signals

reading the documentation may like many, but i will not say
that but angular documentation changes my

perspective

we can use many values in signals from primitives to complex
data structures

angular signal is two types

we can use it only for reading the values this type
does not allows us to change the values
and another type is can we can do read and write

signals was either writable or read-only

how to use the signal in the angular

for using signal we have to import in the angular component

import { signal } from '@angular/core';

const count = signal(0);

using them in the javascript

count()

using them in the template

count()

we have two way to change the value signal they are

set() and update()

this two are function we are getting

form the signal

count.set(3);

count.update((value) => value + 1);

changing the values using the angular event binding

// in template
<button (click)="incrementCount()">+1</button>


// in typescript 
count = signal(0);

incrementCount() {
  this.count.update(val => val + 1);
}

we actually saw that signal has read only and writable

now how to convert the writable signal to read only signal

by using asReadonly() function can make a signal

to read only signal, this function actually takes a copy of the
signal and make it as read only values having signal

Computed signals

it is actually read only signal it actually derives its

value from other signals.

suppose if you like to deside the value type for the

signal we can do it by the WritableSignal

import { WritableSignal, signal, Signal } from '@angular/core';

const count: WritableSignal<number> = signal(0);

suppose if you want to use the type for read only signal
we can use the Signal type

const doubleCount: Signal = computed(() => count() * 2);


import { signal, computed } from '@angular/core';

const price = signal(10);

const doublePrice = computed(() => price() * 2);

we know that computed value is read only, and it actually derived

value form the other signal that means if we change the value of

the original signal does that affects the computed signal, yes

actually yes whenever if you change the signal it affects the

computed signal and so it is lazily evaluated.

Note it actually depends the signal value but it does not depends

value of the signal it actually expects the signal changes

effect signal

if you want to track an value and based on the value if you want

to do any action you can use the effect,

if you use any values inside the effect it will be automatically

becomes the dependencies, if you use any signal inside effect. if the

signal changes effect will automatically starts runs

effect(() => {
  console.log(`User set to ${currentUser()} and the counter is ${counter()}`);
});

it is an example form the angular

suppose if you are using the eventlistner, setInterval and setTimeout.

effect((onCleanup) => {
  const timer = setInterval(() => {
    console.log('Tick...');
  }, 1000);

  onCleanup(() => clearInterval(timer)); 
});

july 12 blog

boopalan — Sun, 19 Jul 2026 12:40:33 +0000

july 11 blog

boopalan — Sun, 19 Jul 2026 12:37:09 +0000

Meeting Minutes, July 2026 | ILUGC

Here is the quick recap of what happend in ILUGC Monthly meet, July 11, 2026. Intro Gopi welcomed the participants and gave small introduction about ILUGC Briefed participants about the mailing list Talk 0 Zaid started his talk explaining network fundamentals He explained the physical and hardware layer Discussed MAC, IPV4 and Subnetting He demonstrated concepts using cisco packet tracer

ilugc.in

i am went to chennai to attent the ilugc meet

july 10 blog

boopalan — Sun, 19 Jul 2026 12:35:15 +0000

Update 16 files (354b87ea) · Commits · Boopalan S / TamilEuphonic · GitLab

- /euphonic/stackwords.py - /euphonic/previous.py - /euphonic/utils.py - /euphonic/wordsbetween.py - /euphonic/singleletter.py - /euphonic/partical.py - /euphonic/specificword.py - /euphonic/common.py - /euphonic/__pycache__/previous.cpython-312.pyc - /euphonic/__pycache__/singleletter.cpython-312.pyc - /euphonic/__pycache__/stackwords.cpython-312.pyc - /euphonic/__pycache__/common.cpython-312.pyc - /euphonic/__pycache__/wordsbetween.cpython-312.pyc - /euphonic/__pycache__/specificword.cpython-312.pyc - /euphonic/__pycache__/utils.cpython-312.pyc...

gitlab.com

i am made a drastic changes in this repo

just look the angular docs, what are the things are for angular 17 to 22

https://angular.dev/overview

What is Angular?

Angular is a web framework that empowers
developers to build fast, reliable applications that users love.

it is from the angular docs

July 9 blog

boopalan — Sun, 19 Jul 2026 12:29:12 +0000

DOM
Document Object Model

Before diving into the DOM, we must know the parents, children, siblings tags in the HTML, and a good understanding in the CSS.

In windows document every thing, can can define it with the name root, origin.

Let see what was we are getting in if we try to log the document in javascript

console.log(document)

Is the document an object?
Yes, a document is an object and if we remove the body for the document object the browser window becomes empty.

How to get the body for the document, let we try to get the body from the document object

console.log(document.body)

What are the things we can able to get from the document object

Just like the body, the head is also the sibling to the body, right so we must get something.

console.log(document.head)

need to learn and write more on this topic

July 8 blog

boopalan — Sun, 19 Jul 2026 12:20:16 +0000

As the continuation of the previous libre office impress i am create an animated matrix multiplication there is lot more needed to do in this, but i am happy to share that what i am done today

It seems like we are again going to restructure Tamilrulepy, really it holds a special place in my heart.

So, I am thinking Instead of abandoning of this workflow I am just planning to keep this code alive revisit it in the future,

Some would think giving up a closer one is a bit emotional, but I am eagerly waiting for the new workflow.

My learnings in python

decorator

A simple and easier way to define an instant decorator in python is easy.

If you see in some places developers will use three functions for defining decorator

One interesting thing i get is we can call decorator while using them in the top of the functions

@decorator
@decorator()

Calling a decorator in these two different ways helps to achieve several things.