2
Homework Assignment-3
1) TABLE PRIMARY KEY FOREIGN KEY(S) EMPLOYEE
EMP_ CODE
STORE_CODE
STORE STORE-CODE
REGION_CODE_,EMP_CODE
REGION
REGION-CODE
None
2)
TABLE ENTITY INTEGRITY EXPLANATION Employee
Yes Each EMP_CODE value is unique and there are no nulls.
Store Yes
Each STORE value is unique and there are no nulls
Region
Yes
Each REGION value is unique and there
are no nulls
3)
TABLE REFERENTIAL INTEGRITY EXPLANATION Employee
Yes
Each STORE-CODE value in employee points an exiting STORE-CODE value in store.
Store
Yes
Each REGION_CODE value in STORE points to an existing REGION_CODE value in REGION and each EMP_CODE value in STORE points to an existing EMP_CODE value in EMPLOYEE Region
NA
4)
The REGION CODE values occur more than once in STORE suggests that each REGION may contain a number of stores. Since every STORE is limited to a single REGION, every STORE, and every REGION has a M:1 link. Naturally, it is also true that there is a 1:M relationship between REGION and STORE.
