DBMS Languages, Interfaces, and Classification

Data Definition Language (DDL)

• For specifying conceptual schema

Storage Definition Language (SDL)

• For specifying the internal schema

View Definition Language (VDL)

For specifying user views and their mappings to the conceptual

Data Manipulation Language (DML)

• For manipulation of data in the database

• High-level/Non-procedural DML

  • Specify DB operations in a concise manner

  • Set-at-a-time DML

• System analysts and programmers design and implement a special interface for parametric users

Interfaces for the Database Administrator 

• Privileged commands

• Ex. creating accounts, granting access, etc. used only by the DB Administrator’s staff

• Based on the following criteria:

  • Data Model

  • Number of Users

  • Cost of DBMS

  • Number of sites

  • Types of access path

  • Generality

DBMS is classified based on what criteria?

Relational Data Model

• Represents DB as a collection of tables

Object-Oriented Database Model

• Defines DB in terms of objects, properties, and operations

Hierarchical Model (legacy model)

Data as tree structures

Network Model (Legacy Model)

• Objects and their relationships in the form of a graph

• Legacy models are not commonly used due to their complexity

Single-user System

• One user only

Multi-user System

Concurrency

Centralized Database System

DB and DBMS stored at a single computer site

Distributed Database System

Distributed over many sites, connected by a computer network