1Introduction to relationaldatabasesINFO/COM S 230:Intermediate Web Design andProgrammingWhat is…?Adatabaseis a collection of related data.Adatabase management system (DBMS,database system)is a piece of softwareused to manage a database efficiently,so that it will persist safely over longperiods of time.The data in the table is certainly a database. Butthe program isn’t a DBMS. Why not?A DBMS…• Allows for persistent storage of very largeamounts of information, and efficient accessto it.• Implements a “query language” (SQL) tostore, access, and modify the data.• Can enforce that the stored data is consistentin certain ways.• Allows for concurrent access by many users.Why?Why might we prefer to use a DBMS towriting our own program for databaseaccess?•DBMSes already exist; don’t have to write things fromscratch (especially tricky things like concurrentaccess, recovering from crashes, etc.)•Don’t need to think about how data is stored; asimple interface via SQL (i.e. no worrying about fileformat – are we using \t as a delimiter??)•Can write quite powerful queries very simply via SQL;don’t need to write a program for each one.•Security; allowing only some users access to somedata.Easy PDF Creator is professional software to create PDF. If you wish to remove this line, buy it now.
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