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• The design of a DBMS depends on its architecture.
• The architecture of a DBMS can be seen as either single tier or multi-tier.
• In 1-tier architecture, the DBMS is the only entity where the user directly sits on the DBMS and uses it. Any changes done here will directly be done on the DBMS itself. It does not provide handy tools for end- users.
• If the architecture of DBMS is 2-tier, then it must have an application through which the DBMS can be accessed. Programmers use 2-tier architecture where they access the DBMS by means of an application.
• Database (Data) Tier − At this tier, the database resides along with its query processing languages.
• Application (Middle) Tier − At this tier reside the application server and the programs that access the database. End-users are unaware of any existence of the database beyond the application. Hence, the application layer sits in the middle and acts as a mediator between the end-user and the database.
• User (Presentation) Tier − End-users operate on this tier (ex - GUI)and they know nothing about any existence of the database beyond this layer. At this layer, multiple views of the database can be provided by the application. All views are generated by applications that reside in the application tier.