Lunes, Agosto 29, 2011

✿Hierarchical model vs Flat file database model


Hierarchical Model

hierarchical data model is a data model in which the data is organized into atree-like structure. The structure allows representing information using parent/child relationships: each parent can have many children but each child only has one parent (also known as a 1:many ratio ). All attributes of a specific record are listed under an entity type.In a database, an entity type is the equivalent of a table; each individual record is represented as a row and an attribute as a column. Entity types are related to each other using 1: N mapping, also known as one-to-many relationships. this model is recognized as the first data base model created by IBM in the 1960s. The most recognized and used hierarchical databases areIMS developed by IBM and Windows
Flat File database model
A flat file database is a database that stores data in a plain text file. Each line of the text file holds one record, with fields separated by delimiters, such as commas or tabs. While it uses a simple structure, a flat file database cannot contain multiple tables like a relational database can. Fortunately, most database programs such as Microsoft Access and FileMaker Pro can import flat file databases and use them in a larger relational database.Flat file is also a type of computer file system that stores all data in a single directory. There are no folders or paths used organize the data. While this is a simple way to store files, a flat file system becomes increasingly inefficient as more data is added. The original Macintosh computer used this kind of file system, creatively called the Macintosh File System (MFS). However, it was soon replaced by the more efficient Hierarchical File System (HFS) that was based on a directory structure.

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