Use the ERD of a school database in Figure $8\mathrm{.}15$ to answer questions $6$ to $9.$

$6.$ Identity all the kernels and dependent and characteristic entities in the ERD.

Kernel: From the table above the kernels are the table which has no foreign key$($i$.$e$.)$

The table with no foreign key are Instructor, Course, Student and Offering.

Characteristics: Attendance is considered as Characteristic entities as it consists of student ID which gives information about student table.

$7.$ Which of the tables contribute to weak relationships? Strong relationships?

Here attendance is the weak entity or table which has weak relationships. Instructors and Instructor have a strong relationship.

$8.$ Looking at each of the tables in the school database in Figure $8\mathrm{.}15,$ which attribute could have a NULL value? Why?

Here in student table fax no can be null because they do not have fax no$,$ again a student may or may not have passport program, so this attribute can be null, company$\_$id can also have null. In instructor table mentor$\_$id can be null because instructor may or may not be a mentor.

$9.$ Which of the tables were created because of too many relationships?

One$-$to$-$many: This relationship allows a single row at one table to be linked with multiple rows in another table. A common example is a customer who can place multiple orders, where each order is linked back to one customer.