User.find(1)
User.find(1, 7, 14)

You can find the first, last, and all records by passing a symbol as the first argument. There are also shortcut methods for accessing these records.

User.find(:all)         User.all
User.find(:first)       User.first
User.find(:last)        User.last

Rails automatically generates a number of dynamic find methods based on your table’s design. This makes it easy to find records quickly.

User.find_by_email('jared@modsognir.com')

You can find first, last, and all by adding the word after ‘find’ in the chain.

Article.find_all_by_user_id(1)
Article.find_first_by_email('j@modsognir.com')

And it is easy to find based on multiple columns too.

User.find_first_by_user_name_and_password('Jared', password)

This covers simple cases. As you delve further into your project, you’ll likely require more complicated searches. Passing a hash as the last argument allows you to pass more refined information into the query.

The ‘:conditions’ option has two modes. The first, by passing a hash, uses AR to form your database query. This abstracts the SQL to Rails, and ensures database compatability as well as protecting from SQL injection attacks.

User.find(:first, :conditions => { :username => 'Jared', :password => password })

The second is accessed either by passing an Array or a String. You should use this only if you are familiar with SQL syntax and need more specialised cases. . These two queries are identical.

User.find(:first, :conditions => "username LIKE #{user.username}")
User.find(:first, :conditions => ["username LIKE ?", user.username])

The Array form will also protect you from SQL injection attacks (while the string wont). It works by having a string as the first element containing SQL, then any question mark in that string will be replaced one by one by the remaining elements.

User.find(:first, :conditions => ["username LIKE ? AND email LIKE ?", user.username, user.email])

When you need to have the returned records ordered in a particular way, use the ‘:order’ option. This takes a string as basic SQL.

User.find(:all,  rder => "created_at DESC")
User.find(:all, :conditions =>; { :role => "admin" },  rder => "username ASC")

Rails -> MySQL
:binary -> blob
:boolean -> tinyint(1)
:date -> date
:datetime ->datetime
:decimal -> decimal
:float ->float
:integer -> int(11)
:string -> varchar(255)
:text -> text
:timestamp -> datetime
:time -> time