4 6 4 Access Route Considerations

Following are some important considerations when defining access routes:

Access routes should always be defined in both directions, i.e. from file A to B and from file B to A.

The Maximum Records parameter is important as it defines the cardinality of the file relationships. This parameter specifies the number of records that are expected to be found in the Accessed File that have a key matching the Key Fields/Values. This value is only significant in that it is one or more than one. If it is one, then a 1:1 relationship between the files is established, (for example, Employee works in a Department). If it refers to more than one, then a 1:many relationship is established. (for example, a Department has many Employees).

Remember that access routes work both ways. If there is an access route from FILE1 to FILE2, then there should also be a corresponding access route from FILE2 to FILE1. For example, Department file has a 1:M relationship to the Employee file and the Employee file will have a 1:1 relationship to the Department file.

When dealing with multiple parent-child relationships, it can be valuable to include access routes from the grandparent to the grandchild. These type of links are particularly useful to reporting tools like LANSA Client which can create a drill down report by following the access routes.

Access routes are very useful for both developers and end-users, in the case of LANSA Client. It is important to take the time to add access routes to your application databases.

Access routes can be used with Other files. They can be used to document the file relationships within your existing application databases.