Active Record Associations

Topics

What is an Association?
Auto-generated methods
How to implement Association?
Cardinality
Eager loading Association

What is and Why Use Associations?

What is an Association?

Represent relationship between database tables, whose relationship is constructed through foreign keys or join table
- Examples: "A Customer has many Order's" or "An Order belongs to a Customer".
Cardinality relationship
- One-to-one: A person has a single primary address
- One-to-many: A school has many students
- Many-to-many: A course has many students and each student take many courses

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Mr. Shin covered everything on Ruby on Rails. I learned a lot from him. His code camp is very intensive and if you follow every lessons and do lab exercises, you will be in no time , become a professional developer.

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The 5-day Ruby on Rails Programming class led by Sang Shin has been great. I have been auditing the class all week thanks to Sang placing a notice on the SF Ruby meetup list and have learned a lot this week. I especially appreciate the 'create code, watch it fail, then flesh it out until it passes' mode of construction, the repetition of commands over the course of several days (after a while it starts to make sense), and the avoidance, for the most part, of using shortcuts so that we could see what' going on at a detailed level. There is a lot of material to pack into only five days, and I feel Sang did an excellent job of doing that while giving just enough time for students to do the exercises along the way. Thanks for this opportunity.

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Active Record Associations

Topics

What is and Why Use Associations?

What is an Association?

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