Situation 4: association through non-key columns

Relationship between root and non-root tables - situation 4:

The root and non-root table are joined using the taskNumber. In this case the relation can have any direction: refer from root to non-root table or from non-root to root table. For that reason no arrow is shown. Note however that the direction must be defined in the BII!

The batchNumber requires a non-related attribute implementation in the BII. Its value must be generated by the implementation when inserting a row on the Task table (during Create or Change).

Note: The value of the attribute(s) that define(s) the relationship must be unique. So for each non-root table row exactly one row exists in the root table, and for each root table row zero or one row exists in the non-root table.