如何与不同计算机/远处的数据库进行交互？ （红宝石）

Question

So, I'm fairly new to dealing with databases, and it makes sense to me when the database is on the local machine. But, how would I deal with a database that is far away/in a different computer? How is the connection set-up? How would I be able to tell Ruby to go toy with that database? I think SQLite is required to be on the local machine, but what about PostgreSQL or MySQL? I'm positive large projects require this sort of set-up with databases somewhere else and whatnot.

Also, this means teams should be able to all interact with the same database, correct?

I've tried finding articles and reading about it, but I can't seem to find any information about this.

Answer 1

In ruby on rails, we have a config/database.yml file where we can do database connectivity. To connect to the remote system's database do:

1 - Give permission to your system to access the database of remote system

Grant all on databasename.* to username@ipaddress of your system identified by password

2 - Update the database.yml file

development: 
 adapter:   mysql  
 database:  databasename  
 username:  username  
 password:  password  
 host:      ip of remote system

Answer 2

Configuring database.yml for your rails app

development:
  adapter: mysql
  database: development_database
  username: root
  password: [password]
  host: localhost
test:
  adapter: mysql
  database: test_database
  username: root
  password: [password]
  host: localhost
production:
  adapter: mysql
  database: production_database
  username: root
  password: [password]
  host: localhost

Answer 3

Don't forget that these databases are not just files that the local program accesses -- they are servers in their own right, and the local program submits requests (select, insert etc) to them for the database server to process and return a result.

This also explains why multiple teams can access the same database -- the database server processes are just communicating with multiple programs at the same time (and the resolution of which program sees which data when they are all accessing and changing the same tables is one of the reasons why databases are so complex).

So the location of the database is only relevant in that it can take longer to send requests to, and retrieve results from, it over the network.