Which is the better way of describing city selections in Maria DB

Question

There is a table of cities in my database. There is a table of clients and a table of forecasts for each city. Every client has a list of cities for which they require forecasts. I need to put these lists in the database for they are in text files now.

I can think of 2 ways to accomplish that:

1. To add a column for each client in city table with Boolean value.
2. To add one column in clients table of type character and put there all city ids separating them with ',' or '_'.

Data will be processed with PHP. DB is small : total of 50 clients and 200 cities.

What I don't like about the first approach is that anytime I have a new client, I need to change the table structure.

I tend to like the second approach more but somehow it doesn't fit into the "DB way" of structuring data.

What do you think?

Answer 1

I don't know mariadb, but you are trying to model a many-to-many relationship.in an SQL database you would create a new table "subscriptions" (or w/e you call it) like this:

user_id  |  city_id  | (additional options if needed)

However in mongodb you would instead (usually) have a list of references (ids):

collection users:
{
   "name": "blabal",
   "cities": [ 1, 2, 7 ]
}

Never do that string variant, it wastes quite a lot of space and is inefficient to search for etc.