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Lecture provides knowledge of database integration. In this chapter, the following content will be discussed: Relational databases, structured query language (SQL), database systems, database access from programming languages. | Ivan Marsic Rutgers University LECTURE: Database Integration http://en.wikipedia.org/wiki/Database http://en.wikipedia.org/wiki/SQL Topics Relational Databases Structured Query Language (SQL) Basics Database Systems MySQL Database Access from Programming Languages What is a Database System? Database: A large collection of related data Shift from computation to information DBMS (database management system): A set of software programs that controls the organization, storage and retrieval of data from databases Database System: DBMS + data (+ applications) Unstructured Data Storage We could use simple text files . Plain text File-1: (each “record” is a new line) "John Doer rented apartment #101 on December 4, 2024" "Jane Deere rented apartment #103 on January 15, 2025" Plain text File-2: "Tenant John Doer entered apartment #101 on February 16, 2025 at 5:30 PM" "Tenant John Doer entered apartment #101 on February 17, 2025 at 5:48 PM" Why Databases? (instead of . | Ivan Marsic Rutgers University LECTURE: Database Integration http://en.wikipedia.org/wiki/Database http://en.wikipedia.org/wiki/SQL Topics Relational Databases Structured Query Language (SQL) Basics Database Systems MySQL Database Access from Programming Languages What is a Database System? Database: A large collection of related data Shift from computation to information DBMS (database management system): A set of software programs that controls the organization, storage and retrieval of data from databases Database System: DBMS + data (+ applications) Unstructured Data Storage We could use simple text files . Plain text File-1: (each “record” is a new line) "John Doer rented apartment #101 on December 4, 2024" "Jane Deere rented apartment #103 on January 15, 2025" Plain text File-2: "Tenant John Doer entered apartment #101 on February 16, 2025 at 5:30 PM" "Tenant John Doer entered apartment #101 on February 17, 2025 at 5:48 PM" Why Databases? (instead of plain/unstructured files) Abstraction More compact and consistent data Query language Data retrieval easier to program and more efficient Data integrity when shared between multiple users Reliability, Recovery, Security, Data-entry validation — all provided by the database system Database Schema Similar to types and variables in programming languages Schema = the structure of the database e.g., the database consists of information about a set of persons and apartments and the relationship between them Analogous to type information of a variable in a program Physical schema: database design at the physical level Logical schema: database design at the logical level Data Organization Data Model = a framework for organizing and interpreting data, describes: data data relationships data meaning (semantics) data constraints or business rules Entity-Relationship (E-R) model a diagramming notation for relational tables and constraints graphically represents relationships between tables .
