LANSA uses access routes to describe relationships between tables in a database. They provide information about the database map or schema. Access routes are simply text descriptions of table relationships in the database. They have no physical impact on the database.
An access route defines to LANSA a route from one table to another table. An access route answers the question: Given that I have a record from table A..... how do I access the associated record(s) in table B?
Table A is always the table definition that is currently being worked upon. Table B can be any other physical table or index defined using the LANSA system.
Table A can have many access routes. They could all be from table A to table B, or some could be to any other table that is related to table A. Access routes are defined in both directions, i.e. from table A to B and from table B to A.
One access route can only define the route from table A to table B. However, table A can have many access routes associated with it. Thus table A can have additional access routes to table C and to table D, etc., etc.
In addition, access routes can be followed in a chain. Thus if there is an access route from table A to table B, and an access route from table B to table C, then it is possible to start with a record from table A and locate the associated record(s) in table C.
Access routes are very important to the automatic process definition components of LANSA because:
Access routes are used in the following ways in LANSA:
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