毕业设计数据库的新应用

毕业设计数据库的新应用内容摘要：

, and video. Today multimedia data typically are stored outside the database, in files systems. When the number of multimedia objects is relatively small, features provided by databases are usually not important. Database functionality bees important when the number of multimedia objects stored is large. Issues such as transactional updates, querying facilities, and indexing then bee important. Multimedia objects often have descriptive attributes, such as those indicating when they were created, who created them, and to what category they belong. One approach to building a database for such multimedia objects is to use database for storing the descriptive attributes, and for keeping track of the files in which the multimedia objects are stored. However, storing multimedia outside the database makes it harder to provide database functionality, such as indexing on the basis of actual multimedia data content. It can also lead to inconsistencies, such a file that is noted in the database, but whose contents are missing, or vice versa. It is therefore desirable to store the data themselves in the database. Forth. Mobility and Personal Databases Largescale mercial databases have traditionally been stored in central puting facilities. In the case of distributed database applications, there has usually been strong central database and work administration. Two technology trends have bined to create applications in which this assumption of central control and administration is not entirely correct: increasingly widespread use of personal puters, and, more important, of laptop or “notebook” puters. development of a relatively lowcost wireless digital munication infrastructure, base on wireless localarea works, cellular digital packet works, and other technologies. Wireless puting creates a situation where machines no longer have fixed locations and work addresses. This plicates query processing, since it bees difficult to determine the optimal location at which to materialize the result of a query. In some cases, the location of the user is a parameter of the query. A example is a traveler’s informa。