find method: The find method is used to find the particular object that matches with the parameter supplied to it.

 article = Article.find(11)     #It is used to find the article whose primary key is 11.
 # => #<Article id: 11, name: "Rahul">

          Sql query be like:

 SELECT * FROM articles WHERE (articles.id = 11) LIMIT 1

This method will raise an ActiveRecord::RecordNotFound exception if it does not find any record in the database.

first method: The first method is used to find the first record that is being ordered by the primary key.

article = Article.first     #It finds the first article in your database.
# => #<Article id: 1, name: "first article">

    Sql query be like:

SELECT * FROM articles ORDER BY articles.id ASC LIMIT 1

This method does not return any exception , it simply returns nil if no record is found.

find_by method: The find_by method is used to find the first record that matches the conditions applied.

 Article.find_by name: 'first article'
 # => #<Article id: 1, name: "first article">

Instead of writing like this you can also write like:

Article.where(name: 'first article')

take method: The take method is used to find a record in which we do not have to pass any order.

article = Article.take
# => #<Article id: 1, name: "first article">

Sql query be like:

SELECT * FROM articles LIMIT 1

last method: The last method is used to find the last record as defined by the primary key.

article = Article.last
# => #<Article id: 122, name: "Virat">

Sql query be like:

SELECT * FROM articles ORDER BY articles.id DESC LIMIT 1