CS31A Midterm Exam

Midterm Exam Study Guide

Databases and Database Users

What is a Database

Data

Information

Metadata

Database

A database management system (DBMS)

Database system

Data redundancy

The main characteristics of the database approach and how it differs from traditional file

systems.

DBMS Architectures

Two-tier architecture

Three-Tier architecture

The three-schema DBMS architecture allows three schema levels:

º An internal schema describes the physical storage structure of the

database.

º A conceptual schema is a high-level description of the whole database.

º External schemas describe the views of different user groups.

Data Independence

Logical Data Independence

Physical Data Independence

Database Languages

Data-Definition Language (DDL)

Data-Manipulation Language (DML)

Database Users and Administrators

The responsibilities of the DBA and the database designers

Database Users

Relational Model Relational Database Model

Relational table

Column ( field or attribute)

Row (tuple or record)

Relation Instance

Relation Schema

Domain

CS31A Midterm Exam

Atomic domain

NULL value

Keys

Primary Key

Foreign Keys

Super key

Composite Key

Candidate keys

Structured Query Language (SQL)

Queries

SQL query structure

SELECT clause

FROM clause

WHERE clause

Data-definition language (DDL), which provides commands for defining relation

schemas, deleting relations, and modifying relation schemas.

CREATE Tables ALTER DROP

Data-manipulation language (DML), which includes a query language and commands to

insert tuples into, delete tuples from, and modify tuples in the database

INSERT, UPDATE, DELETE SELECT statement The use of the IN, BETWEEN, and LIKE operators in WHERE clauses.

JOIN types

º Inner and outer join

º Left, right and full outer join

º Natural, using, and on

Aggregate functions

º avg, min, max, sum, count

º group by

º having

Integrity constraints

Domain constraints

Unique constraint

Check clause