Also used principally with mainframes the network database Brother Cell Phone List is Brother Cell Phone List more flexible than the hierarchical database arrangement, because different relationships may be established between branches of data. However it still requires that the structure be defined in advance. Moreover, these are limits to the number of possible Brother Cell Phone List links among records. Relational Database More flexible then both the databases discussed above, the relational database relates, or connects data in different files through the Brother Cell Phone List use of a key field, or common data element.
In this arrangement there are no access paths down through Brother Cell Phone List a hierarchy. Instead data elements are stored in different tables made up of rows and columns. In database terminology, the tables are called relations (files), the rows are called tuples (records) and the columns are called attributes (fields). All related tables must have a Brother Cell Phone List key field that uniquely identify each row, that is the key field must be in all tables. The advantage of relational databases is that the user does not have to be aware of any Brother Cell Phone List structure. Thus, they can be used with a little training. Moreover, entries can easily be added, deleted or modified. A disadvantage is that some searches can be time-consuming.
Nevertheless, the relational model has become popular for Brother Cell Phone List microcomputer database management programs, such as Paradox and Access. Object-Oriented Database An object oriented database uses "objects," software written in small Brother Cell Phone List reusable chunks, as elements within database files. An object consists of (1) data in any form, including graphics, audio and video, and (2) instructions on the action to be taken on the data. A hierarchical database might contain only numeric and text data but a Brother Cell Phone List student - identification number, name, address and so on.