Final answer:
The hierarchical database is the early style database type known for its inflexible treelike structure. It is less used today compared to the more flexible and scalable relational and object-oriented databases.
Step-by-step explanation:
The database type that is used frequently in early style databases but much less frequently today, which contained inflexible data relationships that formed a treelike structure, is the hierarchical database. Unlike relational databases, which use tables, rows, and columns to store data that can be easily related in many different ways, the hierarchical database model is designed like a tree with connected nodes where each record has a single parent, but can have multiple children. This creates a strict, predefined pattern that can limit the ways in which data is related to each other, making it difficult to adapt to changes or evolving data needs. The flexibility and scalability of relational and object-oriented databases have seen them become preferred over hierarchical databases in modern applications.