country | currency | value |
---|---|---|
Finland | EUR | 1.09 |
Estonia | EUR | 1.09 |
Sweden | SEK | 0.12 |
Countries(country,currency,value)
a → b c | is the same as | a → b
a → c | (a determines both b and c) |
a b → c | is not the same as | a → c
b → c |
a → b b → c | implies | a → c |
a → c b → d c d → e | implies | a b → e |
a b → d | implies | a b c → d |
a → a | an attribute always determines itself |
a b → a | two or more attributes determine a subset of the attributes
(reflexivity + augmentation) |
country | currency | value |
---|---|---|
Finland | EUR | 1.09 |
Estonia | EUR | 1.09 |
Sweden | SEK | 0.12 |
Countries(country,currency,value)
|
|
Consider a database to keep track of room bookings:
code | name | day | timeslot | room | seats |
---|---|---|---|---|---|
TDA357 | Databaser | Tuesday | 0 | GD | 236 |
TDA357 | Databaser | Tuesday | 1 | GD | 236 |
ERE033 | Reglerteknik | Tuesday | 0 | HB4 | 224 |
ERE033 | Reglerteknik | Friday | 0 | GD | 236 |
Consider a database to keep track of room bookings:
code | name | day | timeslot | room | seats |
---|---|---|---|---|---|
TDA357 | Databaser | Tuesday | 0 | GD | 236 |
TDA357 | Databaser | Tuesday | 1 | GD | 236 |
ERE033 | Reglerteknik | Tuesday | 0 | HB4 | 224 |
ERE033 | Reglerteknik | Friday | 0 | GD | 236 |
|
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| ⟹ |
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| ⟹ |
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CompletedCourses(student,course,grade,credits)
student | course | grade | credits |
---|---|---|---|
1 | C1 | G | 5.0 |
2 | C2 | VG | 7.5 |
1 | C4 | G | 9.0 |
4 | C3 | G | 5.0 |
4 | C1 | VG | 5.0 |
2 | C5 | G | 9.0 |
Grades(student,course,grade)
Credits(cource,credits)
|
|
id | name | postcode | city |
---|---|---|---|
1 | Alice | 41279 | Göteborg |
2 | Bob | 43168 | Mölndal |
3 | Carl | 41279 | Göteborg |
|
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Postcodes(city,street,postcode)
city | street | postcode |
---|---|---|
Göteborg | Framnäsgatan | 41264 |
Göteborg | Rännvägen | 41258 |
Göteborg | Hörsalsvägen | 41258 |
Göteborg | Barnhusgatan | 41102 |
Stockholm | Barnhusgatan | 11123 |
Postcodes(city,street,postcode)
|
|
Bookings(code,name,day,timeslot,room,seats)
| ⟹ |
|
course | book | author | teacher |
---|---|---|---|
Databases | DTCB | Ullman | Jonas |
Databases | DTCB | Ullman | Thomas |
Reglerteknik | RTB 1 | Author1 | Lennart |
Reglerteknik | RTB 2 | Author2 | Lennart |