Once entities and attributes in a Vocabulary are mapped to a database, any rule that uses those entities or attributes automatically accesses the database’s tables.

When it comes to reading records, there are two high-level scenarios:

• When you need to retrieve a specific record. To do this, the rule needs to receive a primary key value in input data and use it to retrieve the record.
• When you need to retrieve all records from multiple tables and compare record values across tables. In this case, you do not need a primary key.

Let’s take a look how to model a rule to retrieve a record using a primary key.