$2\mathrm{.}9\mathrm{.}6$: Implementing attribute cardinality.

Refer to the following table diagram:

Course

DepartmentCode

CourseNumber

CourseName U

CreditQuantity $R$

CatalogCode R U

The table is implemented with the following statement:

CREATE TABLE Course $($

DepartmentCode CHAR $(3),$

Coursenumber INT,

CourseName VARCHAR $(30)$ A$\_\text{'}$

Creditquantity TINYINT $-B^{\text{'}}-\text{'}$

CatalogCode CHAR $(3)\_$C$-\text{'}$

$,$ D$\_($DepartmentCode$,$ Coursenumber$)$

What is $A?$Refer to the following table diagram:

F The Course table has columns DepartmentCode, CourseNumber, CourseName U$,$ CreditQuantity R$,$ and CatalogCode R U$.($DepartmentCode$,$ CourseNumber$)$ is the primary key.

The table is implemented with the following statement:

CREATE TABLE Course $($

DepartmentCode CHAR$(3),$

CourseNumber INT,

CourseName VARCHAR$(30)\_\_$A$\_\_,$

CreditQuantity TINYINT $\_\_$B$\_\_,$

CatalogCode CHAR$(3)\_\_$C$\_\_,$

$\_\_$D$\_\_($DepartmentCode$,$ CourseNumber$)$

$)$;

$1)$

What is A$?$