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* = primary key (PK) @ = foreign key (FK) ^ = unique field (UNI) St_Maj_Adv(Student_id*, Major, Advisor*) Decided on PKs 111 Physics Smith 111 Music Chan 320 Math Dobbs 671 Physics White 803 Physics Smith The semantic rules (business rules applied to the database) for this table are: 1. Each Student may major in several subjects. 2. For each Major, a given Student has only one Advisor. 3. Each Major has several Advisors. 4. Each Advisor advises only one Major. 5. Each Advisor advises several Students in one Major. 3NF: Cannot add an advisor withour a student. Deleting a student destroys major and advisor information. Updating advisors must also update the major correctly. So we create tables for students and advisors. Then link them with a St_Adv table. St(Student_id*) 111 320 671 803 Adv_Maj(Advisor*, Major) Smith Physics Chan Music Dobbs Math White Physics St_Adv(Student_id*@, Advisor*@) 111 Smith 111 Chan 320 Dobbs 671 White 803 Smith