The network structure is similar to the tree structure, in that it is composed of nodes and paths. However, and node can be linked to any other node, and entry to the system can be at more than one point. By definition, a network structure must include at least one lower level node that is linked to 2 or more higher level nodes. A diagram of a network structure follows on the other projector. Like the tree structure, network structures are best suited to situations where the information demands are relatively static.
Network structures facilitate analysis of more complex relationships than tree structures.
Both network and tree structures suffer from a lack of flexibility. These tables can be cross referenced to provide powerful filtering and retrieving facilities. To construct a relational database, one first needs to identify the set of needed tables, and then determine what fields to include in each table. The allocation of fields to tables is governed by a process known as normalisation. The purpose of normalisation is to minimise data redundancy, and increase the flexibility of the database.