In this lab, we're going to work on establishing relationships between tables. You should have already read about table relations and foreign keys in the SQL Book. Let's practice making tables that are related to one another through foreign keys.

Let's create a few tables:

1. schools
2. courses
3. students

One school might have one or more courses, so it's fitting to have a separate table for courses, instead of having multiple columns on the schools table for each potential course. To make the connection between a school and it's courses, we'll make a column on the courses table called school_id, where each record is going to point to a corresponding record in the schools table (via the foreign key school_id matching a school's id).

Students can take multiple courses and courses can have multiple students enrolled. The way to represent this will be through a join table. Let's call it enrollments. Join tables are sometimes just referred to by combining the names of the two tables they're joining (so in this case, it could be students_courses), but we're going with enrollments because that just makes sense. Additionally, an enrollment is an actual object: we might add columns/attributes to the table later on.

Let the spec/create_spec.rb guide you on how the tables look. Write your CREATE statements in lib/create.sql.

• All about Joins: the 3 Ring Binder Model

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