references : Database System Concepts (Abraham Silberschatz, Henry F. Korth, S. Sudarshan) .. brought to you by www.itmbali.com

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2. Intro to the
Relational Model
DATABASE SYSTEM`
putu.sundika@gmail.com
References : Database System Concepts (Abraham Silberschatz, Henry F. Korth, S. Sudarshan)

3. Structure of Relational Databases
Relational Database consists of collection of
tables with unique tables name
Column
header
(field or
attribute)
Instructors Table
(information about instructor) row (record) Courses Table
(information about courses)
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4. Structure of Relational Databases
relations refers to a tables, tuples refers to rows and attributes/fields refers to column of a table
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5. Teaches relation
Department relation
Database Schema
Section relation
Relation Schema :
 Department (dept_name, building, budget) Instructor relation
 Teaches (id,course_id,sec_id,semester,year)
 Instructor (id,name,dept_name,salary)
 Section (course_id, sec_id, semester …)
 Domain of attribute
 Null value
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6. Keys
 how tuples within a given relation are distinguished  the values of the attribute values of a
tuple must be such that they can uniquely identify the tuple
 Superkey  one or more attributes that, taken collectively, allow us to identify uniquely a
tuple in the relation  ID attribute of the relation instructor
 Candidate Key  combination of NO candidate key such as name and dept_name is sufficient
to distinguish  {ID} and {name,dept_name} are candidate keys
 Primary Key  winner candidate chosen by programmer  ID
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7. Foreign Key
A relation r1, may include among its attributes the primary key of an other relation, r2. This
attribute is called a foreign key from r1, referencing r2.
The relation r1 is also called the referencing relation of the foreign key dependency, and r2 is
called the referenced relation of the foreign key.
Department relation (r2)
Instructor relation (r1)
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8. Schema
Diagram
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9. Relational Operational
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10. Relational Operational
Instructor relation (r1)
Department relation (r2)
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11. RELATIONAL ALGEBRA
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12. TUGAS KELOMPOK
 Rangkum materi hari ini dengan menggunakan kalimat sendiri
 (untuk setiap kelompok) buat relation schema versi sendiri untuk :
1. Facebook
2. Google Plus
3. Gmail
4. Yahoo Mail
5. Blogspot.com
6. Wordpress.com
7. Google Earth
8. Google Drive
9. DropBox
10. Youtube.com
11. Kaskus.com
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