Презентация на тему Intro to databases database management system

efficient, reliable, convenient, and safe
multi-user storage of

and access to massive
amounts of persistent data.

Efficient
Reliable

via “frameworks”
DBMS may run in conjunction with “middleware”

Data-intensive applications may not use DBMS at all

data
Data definition language (DDL)
Data manipulation or query

language (DML)

Database application developer
Database administrator

database systems
Very simple model
Query with high-level languages:

simple yet expressive
Efficient implementations

= actual contents at given point in time
The Relational

Model

= actual contents at given point in time
Database =

set of named relations (or tables)
Each relation has a set of named attributes (or columns)
Each tuple (or row) has a value for each attribute
Each attribute has a type (or domain)

The Relational Model

Student

Dorm

= actual contents at given point in time
Database =

set of named relations (or tables)
Each relation has a set of named attributes (or columns)
Each tuple (or row) has a value for each attribute
Each attribute has a type (or domain)

The Relational Model

Schema – structural description of relations in database
Instance – actual contents at given point in time

Student

Dorm

= actual contents at given point in time
Database =

set of named relations (or tables)
Each relation has a set of named attributes (or columns)
Each tuple (or row) has a value for each attribute
Each attribute has a type (or domain)

The Relational Model

Schema – structural description of relations in database
Instance – actual contents at given point in time

NULL – special value for “unknown” or “undefined”

Student

Dorm

= actual contents at given point in time
Database =

set of named relations (or tables)
Each relation has a set of named attributes (or columns)
Each tuple (or row) has a value for each attribute
Each attribute has a type (or domain)

The Relational Model

Schema – structural description of relations in database
Instance – actual contents at given point in time

NULL – special value for “unknown” or “undefined”

Key – attribute whose value is unique in each tuple
Or set of attributes whose combined values are unique

Student

Dorm

Table Student(ID, name, GPA, photo)


Create Table Dorm
(name

string, unit char(3), CAP integer)

database systems
Very simple model
Query with high-level languages:

simple yet expressive
Efficient implementations

(relational) database
1. Design schema; create using

DDL
2. “Bulk load” initial data
3. Repeat: execute queries and modifications

with GPA > 3.7 applying to Stanford and MIT

only
All engineering departments in CA with < 500 applicants
College with highest average accept rate over last 5 years
Some easy to pose; some a bit harder
Some easy for DBMS to execute efficiently; some harder
“Query language” also used to modify data

students with GPA > 3.7 applying to Stanford
Select Student.ID
From

Student, Apply
Where Student.ID=Apply.ID
And GPA>3.7 and college=‘Stanford’

that includes the followings:
Your name and email.
Your short bio.
Categorize

databases based on your opinion by using any search engine.
Cite all the sources you use.
No copy-paste.