MySQL 8.0

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create table personal(

id int not null auto_increment unique,
name char(20) not null,
age int not null,
city varchar(20) not null default 'Delhi',
key `city`(`city`)
);
insert into personal(name,age,city) values
('anubhav',22,'delhi'),
('rohit',24,'agra');

create table applications(
 app_id int(5) not null auto_increment unique,
 city varchar(20) not null default 'Delhi',
 key `city`(`city`)
);

insert into applications(city) values
 ('kolkata'),
 ('mumbai'),
 ('mumbai'),
 ('delhi'),
 ('agra'),
 ('agra');
select * from personal;










id
name
age
city


1
anubhav
22
delhi

2
rohit
24
agra


select * from applications;


app_id
city


5
agra

6
agra

4
delhi

1
kolkata

2
mumbai

3
mumbai


alter table personal add foreign key(city) references applications(city)