如何在MySQL数据库中设置state与城市之间的关系？

Question

I want to store this type of record

State_Id       state_name
--------------------------
       1       Gujarat
       2       Maharashtra



City_ID         City_name        State_ID
-----------------------------------------
      1         Bhavnagr                1
      2         Rajkot                  1
      1         Mumbai                  2

Answer 1

One would expect that several cities can be found in a state (while a city belongs to a unique state). To represent that 1-N relationship, you would need two tables: one for the cities and one for the states, where the cities table is a child of the states table (meaning that it has a column that references the id of the state it belongs to):

states(state_id, state_name, ...)
city(city_id, state_id, city_name, ...)

Sample create table statements:

create table states (
    state_id int primary key auto_increment,
    state_name varchar(100)
    -- add more columns here as needed
);

create table cities (
    city_id int primary key auto_increment,
    state_id int not null,
    city_name varchar(100),
    -- add more columns here as needed
    foreign key (state_id) references states(state_id)
);