4.6.3 Access Routes in Personnel System Example
Consider the Department, Section and Employee files which are part of the Personnel System Application database.
For the Department file, access routes to both the Employee and Section files are created. The access routes tell LANSA how the Department file will access the other files:
- Department will access the Employee file by using a logical file over PSLMST which is keyed by DEPTMENT. When Department accesses Employee, it will expect to find many records since a Department can have many Employees.
- Department will access the Section file by using the physical file with the DEPTMENT field as the key. When Department accesses Section, it will expect to find more than one record since a Department can have many Sections.
For the Section file, a relationship back to Department and a relationship to Employee are needed.
- Section will access the Department file by using the physical file with the DEPTMENT field as the key. When Section accesses Department, it will expect to find just one record since a Section belongs to just one Department
- Section will access the Employee file by using a logical file over PSLMST which is keyed by DEPTMENT and SECTION. When Section accesses Employee, it will expect to find many records since a Section can have many Employees.
For the Employee file, a relationship back to both the Department and Section files are needed
- Employee will access the Department file by using the physical file with DEPTMENT field as the key. When Employee accesses Department, it will expect to find just one record since a Employee works in just one Department at a time.
- Employee will access the Section file by using the physical file with SECTION field as the key. When Employee accesses Section, it will expect to find just one record since a Employee works in just one Section at a time.
Also See