Database design paradigm
1. Remove a pair of relationships to meet the first paradigm
Such as students selection
Student Name Name This table does not meet the first paradigm Because a student corresponds to multiple courses
2. Separation and primary key does not have a relationship to another table satisfy the second paradigm
Such as the table below
The student name classroom number and student name have no relationship, which is separated to form a classroom table.
3. Not the field of the primary key, can not have one-on-one relationship
Course Nominal Class Name Teacher Name
The teacher name and the teacher have a pair of relationships, because the teacher name and teacher number
