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Material for Database Class.
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Adding various small notes. 5eac6e0b19441fca9a3f70f239d5cbbc4d769976 aubert@math.cnrs.fr 2018-05-17 20:37:14
First pass over! ea1e4f6ddabd91287d10384dc8f28565a762526b aubert@math.cnrs.fr 2018-05-17 19:26:28
Working on notes on normal forms. 58bfcedc6bd6336592a5f93a43ffc0aaf64fa8f6 aubert@math.cnrs.fr 2018-05-16 16:40:12
Initial commit, draft of lecture notes. 200d2739bca881d60c7c9381b16f5a4d6384ff29 aubert@math.cnrs.fr 2018-05-16 15:35:36
Commit 5eac6e0b19441fca9a3f70f239d5cbbc4d769976 - Adding various small notes.
Author: aubert@math.cnrs.fr
Author date (UTC): 2018-05-17 20:37
Committer name: aubert@math.cnrs.fr
Committer date (UTC): 2018-05-17 20:37
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File Lines added Lines deleted
notes/00_Doc_Notes.md 22 0
notes/00_Questions_Notes.md 15 0
notes/00_sum.md 36 113
File notes/00_Doc_Notes.md added (mode: 100644) (index 0000000..c298a0f)
1 Issues:
2 =======
3
4 Having one bib. per section: https://github.com/jgm/pandoc/issues/771
5 Attention, ce n’est pas la même chose que
6 --reference-location=block --reference-links
7 cf. https://pandoc.org/MANUAL.html
8
9 Class:
10 scrartcl?
11 use --top-level-division=chapter?
12
13
14
15 TO DO
16 =======
17
18 - Integrate homework.
19
20 - Make nice drawing
21
22 - Organize scans (FunDep, ER, UML, Rel, Design, Misc?).
File notes/00_Questions_Notes.md added (mode: 100644) (index 0000000..427b438)
1 Add triggers and stored procedures?
2 Pick names from https://www.hillelwayne.com/post/important-women-in-cs/
3
4 Can you make union of different datatypes?
5
6 When you count, do you count null?
7
8 Documents given to students needs to be updated.
9 The one with advanced SQL, for instance.
10
11 cf notes for Lecture 14: weak entity with identifying relation of degree more than 1. Joint filling.
12 Unclear.
13
14 Can an identifying relationship being of mutiplicity more than 1?
15 I.e., a pet is in my DB only if it belongs to a friend, but a pet can belong to more than 1 friend.
File notes/00_sum.md changed (mode: 100644) (index 32568de..d40590c)
... ... author: Clément Aubert
9 9 institute: Augusta University institute: Augusta University
10 10 dir: ltr dir: ltr
11 11 lang: en lang: en
12 numbersections: true
12 13 keywords: keywords:
13 14 - Computer Science - Computer Science
14 15 - Database - Database
 
... ... Mathematical relations, set-theory, first-order predicate logic!
188 189
189 190 # The Relational Data Model and Relational Database Constraints # The Relational Data Model and Relational Database Constraints
190 191
191
192 **Plan:**
193
194 The Relational Data Model and Relational Database Constraints
195
196 1. Concepts
197 1. Domains, Attributes, Tuples and Relations
198 2. Characteristics of Relations
199 3. Notation
200 2. Constraints
201 1. Types of Constraints
202 2. Keys
203 3. Foreign Keys
204 3. Transactions & Operations
205 1. Presentation
206 2. Insert / Delete / Update
207 3. Dealing with Violations
208
209
210 (Next: SQL)
211
212
213 192 **Ressources:** **Ressources:**
214 193
215 194 - Textbook: Ch. 3 - Textbook: Ch. 3
 
... ... Relational data model:
266 245 **Last Time:** **Last Time:**
267 246 Relational model, vocabulary (domain, attribute, tuple, relation, relation scheme, atomic value Relational model, vocabulary (domain, attribute, tuple, relation, relation scheme, atomic value
268 247
248 ## Constraints
269 249
270 ## Types of Constraints
250 ### Types of Constraints
271 251
272 252 Those are constraints on the tuples (there are constraints on the scheme, for instance, "a relation can't have two attributes with the same name"). Those are constraints on the tuples (there are constraints on the scheme, for instance, "a relation can't have two attributes with the same name").
273 253
274 ### Inherent model-based constraints (implicit)
254 #### Inherent model-based constraints (implicit)
275 255
276 256 Those are part of the model. Those are part of the model.
277 257
278 258 - No duplicate tuple - No duplicate tuple
279 259 - Arity must match - Arity must match
280 260
281 ### Schema-based constraints (explicit)
261 #### Schema-based constraints (explicit)
282 262
283 263 Those are parts of the schema Those are parts of the schema
284 264
 
... ... Those are parts of the schema
286 266 - Entity integrity constraint (no primary key value can be `NULL`) - Entity integrity constraint (no primary key value can be `NULL`)
287 267 - Referential integrity constraint (referred values must exists) - Referential integrity constraint (referred values must exists)
288 268
289 ### Application-based constraints (semantics)
269 #### Application-based constraints (semantics)
290 270
291 271 *Cannot* be expressed in the schema, and hence must be enforced by some other way. *Cannot* be expressed in the schema, and hence must be enforced by some other way.
292 272 Example: the date of birth of an employee must be greater than xxx. Example: the date of birth of an employee must be greater than xxx.
293 273
294 ## Keys
274 ### Keys
295 275
296 276 Tuples can't be equal, so a subset of values must distinguish them, we study the corresponding subset of attributes. Tuples can't be equal, so a subset of values must distinguish them, we study the corresponding subset of attributes.
297 277
 
... ... Constraints:
336 316 - Entity Integrity Constraint and Referential Integrity Constraint. - Entity Integrity Constraint and Referential Integrity Constraint.
337 317
338 318
339
340 319 | CAR(\underline{VIN}, Make, Model, Year) | CAR(\underline{VIN}, Make, Model, Year)
341 320 | DRIVER(\underline{State}, \underline{Licence\_number}, Name, Address) | DRIVER(\underline{State}, \underline{Licence\_number}, Name, Address)
342 321 | INSURANCE(\underline{Policy\_Number}, Insured\_Car, Insured\_Driver\_State, Insured\_Driver\_Num, Rate) | INSURANCE(\underline{Policy\_Number}, Insured\_Car, Insured\_Driver\_State, Insured\_Driver\_Num, Rate)
343 322 | PRICE(\underline{Stock\_number}, Car\_Vin, Price, Margin) | PRICE(\underline{Stock\_number}, Car\_Vin, Price, Margin)
344 323
345 ## Presentation
324 ## Transactions And Operations
346 325
347 326 Operations are of two kinds: retrievals and updates. Operations are of two kinds: retrievals and updates.
348 327
 
... ... They are two constraints for updates:
356 335
357 336 Transaction = series of retrievals and updates performed by an application program, that leaves the DB in a consistent state. Transaction = series of retrievals and updates performed by an application program, that leaves the DB in a consistent state.
358 337
359 ## Insert / Delete / Update
338 ### Insert / Delete / Update
360 339
361 340 a., b. and c. refers to the "remedies", on the next page. a., b. and c. refers to the "remedies", on the next page.
362 341
363 ### Insert:
342 #### Insert:
364 343
365 344 `Insert <109920, Honda, Accord, 2012> into CAR.` `Insert <109920, Honda, Accord, 2012> into CAR.`
366 345
 
... ... How things can go wrong:
371 350 - Wrong number of arguments (a.) - Wrong number of arguments (a.)
372 351 - Fail to reference to an existing value for the foreign key (a.) - Fail to reference to an existing value for the foreign key (a.)
373 352
374 ### Delete
353 #### Delete
375 354
376 355 `Delete the DRIVER tuple with State = GA and Licence_number = 123` `Delete the DRIVER tuple with State = GA and Licence_number = 123`
377 356
 
... ... How things can go wrong:
380 359 - Deleting tuples inadvertently (meta) - Deleting tuples inadvertently (meta)
381 360 - Delecing tuples that are referenced (a., b., c.) - Delecing tuples that are referenced (a., b., c.)
382 361
383 ### Update (a.k.a. modify)
362 #### Update (a.k.a. modify)
384 363
385 364 `Update Name of tuple in DRIVER where State = GA and Licence_number = 123 to Georges` `Update Name of tuple in DRIVER where State = GA and Licence_number = 123 to Georges`
386 365
 
... ... How things can go wrong:
392 371 - Change foreign key to a non-existing value (a.) - Change foreign key to a non-existing value (a.)
393 372
394 373
395 ## Dealing with Violations
374 ### Dealing with Violations
396 375
397 376 a. Reject (restrict) a. Reject (restrict)
398 377 b. Cascade (propagate) b. Cascade (propagate)
 
... ... INSERT INTO PROF VALUES (
513 492 - Textbook: Ch. 4, 5 (but warning, describe `SQL`, not one of its implementation) - Textbook: Ch. 4, 5 (but warning, describe `SQL`, not one of its implementation)
514 493 - On-line ressources: cf. homework + web-page - On-line ressources: cf. homework + web-page
515 494
516 **Plan:**
517
518 1. Overview of Constraints
519 2. Foreign Keys
520 3. Restrictions on Foreign Keys
521
522 495 Note: Use `DESCRIBE <TableName>` and `SELECT * FROM <TableName>` intensively to see where you are. Note: Use `DESCRIBE <TableName>` and `SELECT * FROM <TableName>` intensively to see where you are.
523 496 Use `DROP TABLE <TableName>` and `DROP SCHEMA <SchemaName>` for a "fresh start". Use `DROP TABLE <TableName>` and `DROP SCHEMA <SchemaName>` for a "fresh start".
524 497
 
... ... SELECT * FROM Table_set_null;
773 746
774 747 Note: Use `DESCRIBE <Table>;`, `SHOW TABLES;` and `SELECT * FROM <Table>;` intensively to see where you are. Note: Use `DESCRIBE <Table>;`, `SHOW TABLES;` and `SELECT * FROM <Table>;` intensively to see where you are.
775 748
776 **Plan:**
777
778 1. Constructing and Populating a New Example
779 2. A First Look at Conditions
780 749
781 750 ### Constructing and Populating a New Example ### Constructing and Populating a New Example
782 751
 
... ... Take the time to introduce future topics + to give exam back.
1218 1187
1219 1188 --- ---
1220 1189
1221 ## Plan: (for the future lectures)
1222
1223 1. E.R. Models
1224
1225 a. Enties and Attributes
1226 b. Entity Types and Key Attributes
1227 c. Relationships and Structural Constraints
1228 1. Vocabulary
1229 2. Recursive & Role Names
1230 3. Constraints
1231 4. Attributes
1232 5. Relationships of Degree Higher Than 2
1233 d. Weak Entity Types
1234 e. Alternative Notations
1235 f. Enhanced (extended) Entity–Relationship (EER) Models
1236 g. Reverse Engineering
1237
1238 2. E.R.-to-Relational Models Mapping
1239
1240 3. Guidelines and Normal Forms
1241
1242 a. General Rules
1243 b. Functional Dependencies
1244 c. Normal Forms and Keys
1245
1246 4. UML Diagram
1247
1248 a. Overview
1249 b. Types of Diagrams
1250
1251 1190 **Textbook:** **Textbook:**
1252 1191
1253 1192 - E.-R. models: Chapter 7 - E.-R. models: Chapter 7
 
... ... Take the time to introduce future topics + to give exam back.
1255 1194 - Normalization: 15 - Normalization: 15
1256 1195 - UML: not so much in the textbook, but you can look at 7.8 and 10.3 - UML: not so much in the textbook, but you can look at 7.8 and 10.3
1257 1196
1258 ## E.R. Models
1197 ## Entity-Relationship (ER) model
1259 1198
1260 1199 Data = entity, relationships, attributes Data = entity, relationships, attributes
1261 1200
 
... ... Naming convention:
1337 1276 ![](paper_screen/Relationship_instance.jpeg){ width=100% } ![](paper_screen/Relationship_instance.jpeg){ width=100% }
1338 1277
1339 1278
1340 #### Recursive
1279 #### Recursive And Role Names
1341 1280
1342 1281 Convenient, and sometimes mandatory, to give role names: Convenient, and sometimes mandatory, to give role names:
1343 1282
 
... ... Crow's foot notation:
1435 1374
1436 1375 <https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#Crow%27s_foot_notation> <https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#Crow%27s_foot_notation>
1437 1376
1438 ## E.E.R. Models
1377 ## Enhanced Entity–Relationship (E.E.R) Model
1439 1378
1440 1379 Extended (or Enhanced) E.R. Models have additionaly: Extended (or Enhanced) E.R. Models have additionaly:
1441 1380
 
... ... Closer to OO programming.
1446 1385
1447 1386 ## Reverse Engineering ## Reverse Engineering
1448 1387
1449 From Rel. Models to E.R. models (sometimes needed)
1388 From relational models to E.R. models (sometimes needed)
1450 1389
1451 1390 ![](paper_screen/Reverse_Eng1.jpeg){ width=100% } ![](paper_screen/Reverse_Eng1.jpeg){ width=100% }
1452 1391
 
... ... Multivalued attribute | Relation and foreign key
1508 1447 Value set | Domain Value set | Domain
1509 1448 Key attribute | Primary key Key attribute | Primary key
1510 1449
1511 Need to work on a better example, includings n-ary relationship, and propagate options.
1512
1513 ---
1514
1515 + Propagate option? Cascade, most of the time: weak entity type, lookup tables, etc.
1450 **Worked on PB 2 and 3 of HW4, that needs to be adapted. Needs to be written more properly. Cf. Drawing in Lecture 16's notes.**
1516 1451
1452 **Need to work on a better example, includings n-ary relationship, and propagate options.**
1517 1453
1518 ### Outro
1454 **+ Propagate option? Cascade, most of the time: weak entity type, lookup tables, etc.**
1519 1455
1520 E.R. Model | Relational Model
1521 --- | ---
1522 Entity type | Entity relation
1523 1:1 or 1:N relationship type | Foreign key (or relationship relation)
1524 M:N relationship type | Relationship relation and two foreign keys
1525 n-ary relationship type | Relationship relation and n foreign keys
1526 Simple attribute | Attribute
1527 Composite attribute | Set of simple component attributes
1528 Multivalued attribute | Relation and foreign key
1529 Value set | Domain
1530 Key attribute | Primary key
1531
1532 **Worked on PB 2 and 3 of HW4, that needs to be adapted. Needs to be written more properly. Cf. Drawing in Lecture 16's notes.**
1533 1456
1534 1457 ## Guidelines and Normal Form ## Guidelines and Normal Form
1535 1458
 
... ... BRAND(Name, Email)
1615 1538
1616 1539 Brand, Name and Name being the ID. Brand, Name and Name being the ID.
1617 1540
1618 ## Functional Dependencies
1541 ### Functional Dependencies
1619 1542
1620 1543 Formal tool to assess how "good" a database is, a property of the relation schema. Formal tool to assess how "good" a database is, a property of the relation schema.
1621 1544
1622 ### Using Semantics of Attributes
1545 #### Using Semantics of Attributes
1623 1546
1624 1547 "What *should* be." "What *should* be."
1625 1548
 
... ... Think about their dependencies, and list them:
1637 1560 - `TEACHER.Office` → `TEACHER.Phone` - `TEACHER.Office` → `TEACHER.Phone`
1638 1561 - `MAKER.Owner` and `MARKER.Color` → `MARKER.Brand` ? - `MAKER.Owner` and `MARKER.Color` → `MARKER.Brand` ?
1639 1562
1640 ### Using Relation States
1563 #### Using Relation States
1641 1564
1642 1565 "What *is*.", can disprove some of the assumptions made previously, but shouldn't add new dependencies based on it (they may be by chance!). "What *is*.", can disprove some of the assumptions made previously, but shouldn't add new dependencies based on it (they may be by chance!).
1643 1566
 
... ... Att. 3 → Att. 2 | Att. 3 → Att. 2
1662 1585 Att. 1 → Att. 3 | Att. 2 → Att. 1 Att. 1 → Att. 3 | Att. 2 → Att. 1
1663 1586 {Att. 1, Att. 2} → Att. 3 | {Att. 3, Att. 2} → Att. 1 {Att. 1, Att. 2} → Att. 3 | {Att. 3, Att. 2} → Att. 1
1664 1587
1665 ### Notations
1588 #### Notations
1666 1589
1667 1590 Functional dependencies list the constraints between two sets of attributes from the database. Functional dependencies list the constraints between two sets of attributes from the database.
1668 1591 X → Y reads "X fixes Y", and applier that values in Y are fixed by the value in X. X → Y reads "X fixes Y", and applier that values in Y are fixed by the value in X.
 
... ... Note that:
1685 1608 - Transitivity: If X → Y and Y → Z, then X → Z - Transitivity: If X → Y and Y → Z, then X → Z
1686 1609
1687 1610
1688 ### Definitions
1611 #### Definitions
1689 1612
1690 1613 Remember superkey (not minimal key), key, candidate key, secondary key? Remember superkey (not minimal key), key, candidate key, secondary key?
1691 1614
 
... ... A FD : X → Y is a **transivive dependency** if there exist a set of attribute
1714 1637 --- ---
1715 1638
1716 1639
1717 ## Normal Forms and Keys
1640 ### Normal Forms and Keys
1718 1641
1719 1642 First, Second, Third, Fourth, Fifth normal form ("X"NF). First, Second, Third, Fourth, Fifth normal form ("X"NF).
1720 1643 Stronger than the Third, there is the Boyce-Codd NF (BCNF) Stronger than the Third, there is the Boyce-Codd NF (BCNF)
 
... ... Stronger than the Third, there is the Boyce-Codd NF (BCNF)
1722 1645 If you satisfy $N$, you satisfy $N-1$, $N-2$, etc. If you satisfy $N$, you satisfy $N-1$, $N-2$, etc.
1723 1646 The *normal form* of a relation is the highest normal form condition that it meets. The *normal form* of a relation is the highest normal form condition that it meets.
1724 1647
1725 ### Fist Normal Form
1648 #### Fist Normal Form
1726 1649
1727 #### Definition
1650 ##### Definition
1728 1651
1729 1652 The domain of all attributes must be atomic (simple, indivisible): exclude multi-valued and composite attributes. The domain of all attributes must be atomic (simple, indivisible): exclude multi-valued and composite attributes.
1730 1653
1731 1654 Sometimes, additional requirement that every relation has a primary key. Sometimes, additional requirement that every relation has a primary key.
1732 1655 We will take this requirement to be part of the definition of 1NF, but some authors take a relation to be in 1NF if it has at least candidate keys (i.e., multiple possible keys, but no primary key, which makes their definition more general, cf. [@Textbook7, 14.4.1]). We will take this requirement to be part of the definition of 1NF, but some authors take a relation to be in 1NF if it has at least candidate keys (i.e., multiple possible keys, but no primary key, which makes their definition more general, cf. [@Textbook7, 14.4.1]).
1733 1656
1734 #### Normalization
1657 ##### Normalization
1735 1658
1736 1659 **To be written** **To be written**
1737 1660
1738 ### Second Normal Form
1661 #### Second Normal Form
1739 1662
1740 #### Definition
1663 ##### Definition
1741 1664
1742 1665 1NF + Every non-prime attribute is fully functionnaly dependent on the primary key. 1NF + Every non-prime attribute is fully functionnaly dependent on the primary key.
1743 1666
1744 #### Normalization
1667 ##### Normalization
1745 1668
1746 1669 For each attribute $A$ of the relation whose primary key is $A_1, ..., A_n$: For each attribute $A$ of the relation whose primary key is $A_1, ..., A_n$:
1747 1670
 
... ... Refinment: note that if more than one attribute depends of the same subset $\{A'
1762 1685
1763 1686 Note also that if our primary key is a singleton, then there is nothing to do, we are in 2NF as soon as we are in 1NF. Note also that if our primary key is a singleton, then there is nothing to do, we are in 2NF as soon as we are in 1NF.
1764 1687
1765 ### Third Normal Form
1688 #### Third Normal Form
1766 1689
1767 #### Definition
1690 ##### Definition
1768 1691
1769 1692 2NF + no non-prime attribute is transitively dependent on the primary key. 2NF + no non-prime attribute is transitively dependent on the primary key.
1770 1693
1771 #### Normalization
1694 ##### Normalization
1772 1695
1773 1696 For each attribute $A$ of the relation whose primary key is $A_1, ..., A_n$: For each attribute $A$ of the relation whose primary key is $A_1, ..., A_n$:
1774 1697
 
... ... For each attribute $A$ of the relation whose primary key is $A_1, ..., A_n$:
1786 1709 **ADD EXAMPLES** **ADD EXAMPLES**
1787 1710
1788 1711
1789 ### Notes And Examples
1712 #### Notes And Examples
1790 1713
1791 1714 CCL: every FD X → Y s.t. X is a proper subset of the primary key, or a non-prime attribute, is problematic. CCL: every FD X → Y s.t. X is a proper subset of the primary key, or a non-prime attribute, is problematic.
1792 1715
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