You can apply a unidirectional updating system to a hierarchical system with the following characteristic:

• Only information on updates to a higher-level database needs to be imported into lower-level databases. There is no need to import information on updates to a lower-level database into higher-level databases.

The following figure shows a hierarchical system that uses a unidirectional updating system.

Figure 4-24 Hierarchical system that uses a unidirectional updating system

You can apply a bidirectional updating system to a hierarchical system with the following two characteristics:

• Only information that updates a large database, such as the corporate-level database or a division-level database, needs to be imported into lower-level databases; there is no need to import information on updates to a lower-level database into higher-level databases. In this case, the corporate-level and division-level databases use the unidirectional updating system.
• A database with limited information, such as a departmental-level database or a database at an even lower level, shares its information. In this case, the departmental-level and lower-level databases use the bidirectional updating system.

The following figure shows a hierarchical system that uses a bidirectional updating system.

Figure 4-25 Hierarchical system that uses a bidirectional updating system