create database javacourse;
drop database javacourse;
show databases;
show tables;
-- -- -- describe user;
use meri;
create table student(id int primary key auto_increment,username varchar(20),place
varchar(20));
select * from student;
insert into student values(null,'merisha','chennai');
insert into student(username,place) values('maha','chennai');
use student;
select * from student;
alter table student drop column gender;
insert into student values(null,'sanjai','ch'),(null,'sakthivel','chennai'),
(null,'david','ch');
alter table student add gender varchar(20);
update student set place='ariyalur' where id=5;
delete from student where id=2;
desc student;
alter table student modify place varchar(25);
alter table student rename to students;
show tables;
select * from students;
select * from students where place='chennai';
select username from students where place='chennai';
select distinct place from students where place='chennai';
select count(place) from students;
select count(distinct place) from students;
select * from students order by username;
select * from students where username='maha' and place='chennai';
select * from students where username='maha' or place='ch';
truncate students;
drop table students;
select * from students;
drop table students;
show tables;
-- -- -- drop database user;
-- -- --
use ecomm;
select * from users;
create table users(user_id int primary key,username varchar(20),city varchar(20));
CREATE TABLE orders (
order_no INT PRIMARY KEY,
user_id INT REFERENCES users(user_id),
product_id INT REFERENCES books(product_id)
);
INSERT INTO users VALUES (1, 'merisha', 'chennai');
INSERT INTO users VALUES (2, 'gra', 'arak');
INSERT INTO users VALUES (3, 'jen', 'pf');
insert into users values (1, 'merisha', 'chennai'), (2, 'gra', 'arak');
INSERT INTO orders (order_no, user_id, product_id)
VALUES (97, 1, 456);
INSERT INTO orders (order_no, user_id, product_id)
VALUES (76, 2, 27);
INSERT INTO orders (order_no, user_id, product_id)
VALUES (80, 3, 109);
-- use world;
-- select * from users cross join orders;
-- SELECT *
-- FROM users INNER JOIN orders
-- ON users.user_id = orders.user_id;
-- SELECT *
-- FROM users LEFT JOIN orders
-- ON users.user_id = orders.user_id;
-- SELECT *
-- FROM users RIGHT JOIN orders
-- ON users.user_id = orders.user_id;
use student;
create table science(sid int primary key auto_increment,name varchar(25));
create table maths(mid int primary key auto_increment,name varchar(25));
insert into science(name) values('maha'),('sanjai'),('david'),('sakthivel'),
('kirubakaran');
select * from science;
insert into maths(name) values('maha'),('jai'),('jen'),('sakthivel'),('gracy');
select * from maths;
select * from science as s right join maths as m on s.name = m.name;
select * from science as s left join maths as m on s.name = m.name;
select * from science as s inner join maths as m on s.name = m.name;
drop table football;
use student;
use petstore;
use meri;
select * from user;
create database petstore;
use student;
select * from user;
use meri;
select * from user;
