Databases (DB) allow you to store various information in the form of a structured table or an inheritance scheme for elements, which contain the necessary records, grouped by a similar set of properties or parameters and entered in the appropriate cells. There are several types of databases, which differ in structure and purpose of use.
Hierarchical databases
The structure in the hierarchical base is presented in the form of a schema with objects of various levels belonging to one or another data group. There are parent and child elements in the database, i.e. the principles of inheritance and grouping by the type of stored information have been implemented. Structurally, the hierarchical base is a tree of elements. This is how XML documents and the Windows registry are implemented.
For example, there is a database of customers in a store. Each customer purchased a specific product. Thus, if you represent a purchase in a store as a hierarchical database, the parent element will be expressed in a specific customer. The child element will be the purchased goods, which will be associated with each consumer individually. Thus, the buyer Petrov, who bought a DVD player and discs with films, will be the main element. The player and disks will be associated with Petrov and will be child elements in the database.
Networked databases
Network databases are also built on the principle of hierarchy, but they have some difference - each child element can be associated with several parent records, i.e. objects that are located above this cell in the structure.
Thus, each network database is only a complicated hierarchical one. The disadvantage of this type is some confusion when storing large amounts of data, which violates the efficiency of its use when storing information in general.
A striking example of a network base is the Internet, which has a large number of documents that have several parent elements and are interconnected by hyperlinks, i.e. distributed within a single network base.
Relational databases
Today this type of bases is one of the most widespread and widely used due to its structure. All data in such a database is stored in a separate table, which is accessed by accessing a row, column or specific cell directly or using an existing query language or database management system.
The most difficult stage in the development of relational databases is design.
The table indicates the data type, ordinal number, string parameter, text, etc. Each of these elements can be automatically found by the corresponding search query, regardless of the amount of stored data, which makes this type especially effective when performing information storage tasks during the development of sites or extensive information stores.
