Linking in VDM (or any query and reporting tool) is required when requesting data from two or more tables. Linking tells VDM how to join the tables together in order to return the requested data set.
In the examples below we are pulling data from the CLIENT table and the TRANS table. Linking tells VDM that the unique data field in CLIENT is also unique in TRANS. The data for the two tables are joined by the Client_ID field. Linking can be a bit challenging in the beginning, but as you become more comfortable with your data and VDM it will become second nature.
To add a new linking select the field from one table/file, displayed within its own box, and drag it the corresponding field in the table/file that you wish to link. VDM will ask what type of join you would like to do; Equal (=) – Implicit, Equal (JOIN) –Explicit, Left, or Right. If you have more than two tables, repeat the task for each table.
Upon the creation of a new link, VDM will ask if you’d like to remember this link for future use. Selecting yes will store the link and the next time the same tables are selected for a View, VDM will automatically create the linking for you.