What is a Database? SECTION 1

Database Technology and its Evolution Decades long evolution Early data processing systems Today's systems New technology

File-Oriented Systems Early business computer systems Data processing systems Sequential processing Application program

Data from a File- Oriented System

Random Access Processing Limitations of sequential processing systems Sequential processing leads to additional work Solved by :

Limitations of Traditional File Systems Data redundancy Poor data control Inadequate data manipulation capabilities Excessive programming effort

Information as a Resource What is an Information System (IS)? A Management Information System (MIS) Data Information

A database A database system Database Management System

Database Systems Data models Hierarchical model Pointer

Files with a Hierarchical Relationship

CUSTOMER INVOICE LINE

CUSTOMER INVOICE LINE STORE CONTACT

A network model CUSTOMER INVOICE LINE STORE CONTACT SALES REP

Relational Databases Systems Pointers - strengths and weaknesses E.F. Codd (1970)

An Illustration of Problems with Pointers For each customer, identify the manufacturer of the ordered products. CUSTOMER INVOICE LINE MANUFACTURER PRODUCT No physical connection

Codd’s proposal Tables Manipulation languages

Database Systems: Hardware, Software, Data, and People A complete database systems consists of: 1Hardware 2Software –DBMS –Application software

DBMS Data dictionary Data security and integrity

Database Data Item User View 2 User View 3 User View 1

3Data 4People

Database & Instance Disk Memory (RAM) CPU Typical components of a server

Database: The actual database is a collection of tables or files that reside on the disk Memory (RAM) CPU Disk Database Table 1 Table 2 Table 4 Table 3 Table 5 Table n Two main types of database files: Data Metadata

Instance: Software running in memory CPU Disk Database Table 1 Table 2 Table 4 Table 3 Table 5 Table n DBMS Instance Memory (RAM)

An Instance: Multiple databases CPU Disk DB01 Table 1 Table 2 Table 4 Table 3 Table 5 Table n DBMS Instance DB02 Table 1 Table 2 Table 4 Table 3 Table 5 Table n Memory (RAM)

Multiple Instances: Single database CPU Disk Database Table 1 Table 2 Table 4 Table 3 Table 5 Table n DBMS Instance 01 Instance 02 Memory (RAM)

Multiple Instances: Single database CPU02 Disk Database Table 1 Table 2 Table 4 Table 3 Table 5 Table n Memory (RAM) Instance 01 Instance 02 CPU01 Memory (RAM) DBMS

INSTANCE OASIS Multiple databases