One to One

• Both Tables have only one association with one another.
• From a implementation perspective, this involves one table associating one of it’s columns as a foreign key to the primary key of another table.

One to Many

• One table (A) has a lot of associations with another table (B). However B only has one association with (A).
• From a implementation perspective, this involves the many table associating one of it’s columns as a foreign key to the primary key of the one table.

Many to Many

• Both tables have many relationships with one another. Example students can take many courses, and courses can have many students.
• To implement, we must use a joining table. The joining table with have foreign keys linked to the tables with many to many relationships.

Think about a row in a table to the rows in another table

• Say table A and B
• if table A row is connected to one table B row, then one to one
• if table A row is connected to many table B rows, then one to many
• if table A rows are connected to many table B rows, than many to many