Configuration Guidelines > Creating and Modifying Objects >

Constructing Joins

A join defines a logical relationship between the base table of a business component and another table. The join is a child object of a business component. Fields in a business component reference joins. A join should only be used when the resulting database join will retrieve none or only one record. For example, a join is used to retrieve the primary Account for an Opportunity.

A business component may have more than one join with the same destination table if you specify an alias for each join using the Alias property. For example, the Action business component may have two joins to the S_CONTACT table, one to retrieve the owner of the person who created the activity, and another to retrieve the contact associated to the activity. In this example, the joins aliases are Owner and Primary Contact respectively.

It is important that the Alias property of the join be distinct even though the destination table is the same. It is usually not a good practice to use the table name as the Alias name, even though this is common in the standard repository. This is because implicit joins will use the table name as the Alias in order to make sure that the explicit join does not get used instead. To make sure that no conflict exists, you should always give the join a distinct and custom alias name.

There are two types of joins, explicit and implicit.

 Configuration Guidelines 
 Published: 18 April 2003