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What is Database

• A collection of files that store the data

What is Database Management System

• Software that manages the DB
• A big program that accesses and updates those files
• Example of DBMS:

Why we need DBMS

Can we store data without DBMS ?

Problem without an DBMS

Integrity

• The txt files cannot enforce integrity, but DBMS helps us to keep the data correct For example, GPA should be between 0 to 4, and user cannot insert values that are greater than 4.

Scalability

• If we have big datasets,

• the time cost for searching would be unacceptable.
• the main memory can only keep a small fraction of the datasets, and the rest has to stay on disk

Different Views

• The text file solution only allows one view of the data.
• With a DBMS, could arrange for different people to have different views of the data. For example, a professor can see everything, while student can see only his/her data, and a TA can see data for students in his/her section, etc.

Security

• A DBMS will allow multiple levels of security

Crash Recovery

• A DBMS is able to guarantee 100% recovery from system crashes (to a consistent state)