sql programming language code example

Example 1: what is sql

SQL is a domain-specific language used in programming and designed for managing
data held in a relational database management system, or for stream processing
in a relational data stream management system.

Example 2: SQL

CREATE TABLE friends (
   id INTEGER,
   name TEXT,
   birthday DATE
);

INSERT INTO friends (id, name, birthday) 
VALUES (1, 'Jane Doe', '1990-05-30');


INSERT INTO friends(id , name , birthday)
VALUES(2 , 'APOORV' , '2000-2-2');



UPDATE friends
SET name = 'Jane Srivastava'
WHERE id = 1;

ALTER TABLE friends 
ADD COLUMN email TEXT; 


UPDATE friends 
SET email =  '203029@klsafjls'
where id  = 1; 

UPDATE friends 
SET email =  '203029@klsafjls'
where id  = 2;

DELETE FROM friends 
WHERE id = 1;


SELECT * 
FROM friends;

Example 3: what sql language

1- Data Manipulation Language(DML)-(SELECT, INSTERT, UPDATE...)
DML statements affect records in table. These are
basic operations we perform on data such as selecting
few records from a table, inserting new records,
deleting unnecessary records, updating existing records.

2-Data Definition Language (CREATE , ALTER , DROP)...
DDL statements are used to modify database or
table schema. These statements handle the design
and storage of database objects.

3-Data Control Language (GRANT , REVOKE)...
DCL statements control the level of access that
users have on database objects

4- Transaction Control Language (BEGIN TRAN, COMMIT TRAN, ROLLBACK)...

TCL statements allows us to control and manage
transactions to maintain the integrity of data
withing SQL statements.

Example 4: how do you use sql

Our web application uses Oracle database and 
I normally write queries to do Data validation. 
For example: 
I create data from UI or I send POST request
from API then I write query to verify that
data was successfully and correctly inserted
into database. Our database consists of
many tables, so most of the time,
I need to write queries that involve joins.

CAN MENTION: Since our application has
large sets of data, data is stored into
Oracle and to another CACHE database. 
I write queries to test data that both are in SYNC(same).