Моделирование бизнес-процессов / Моделирование бизнес-процессов / ER-диаграмы / 0849315484 Entity-Relationship Diagrams

U

Unique identifier:

Any combination of attributes and/or relationships that serves to uniquely identify an occurrence of an entity.

W

Waterfall model:

A series of steps that software undergoes, from concept exploration through final retirement.

Weak entity:

An entity that is dependent on some other entity for its existence.

Index

A

Atomic attributes, 28, 31, 54, 95, 125, 206

Attribute(s), 8, 9, 13, 25, 26, 27, 40, 41, 42, 53, 73, 136 atomic, 28, 31, 54, 95, 125, 206

closure of, 14

composite, 28-30, 31, 54, 95, 98, 125, 206, 220, 233 definition of, 26

derived, 28-30, 33, 233

intersection, 134, 166, 167, 169, 178, 182 key, 30, 115

multi-valued, 28-30, 32, 44, 45, 54, 116, 134, 220, 226 mapping rule for, 206

reverse-engineering, 215 names, 195, 220 non-atomic, 31

optional versus mandatory, 221 orphaned, 166

relationship, 134

simple, 28, 31, 146, 188, 235 single-valued, 33

specific, 191 suspicious, 58 variant, 190, 191

Augmentation rule, 12

Index

B

Barker/Oracle-like model, 28, 219-231 attributes, 221-222

exercises, 230

first entity-only ER diagram, 220-221 mapping of M:N relationships, 228-229 multi-valued attributes, 226

problem with, 220

recursive relationships, 227-228 relationships, 222-223 structural constraints, 223-224 treatment of foreign keys, 227 weak entity, 225

Binary relationship, 55, 63, 81, 94, 100, 130, 165, 207, 208, 233

Binary relationships, ER diagrams with, 133-164 adding more attributes than evolve into entities, 140

alternative ER notation for specifying structural constraints on relationships, 154-155

attributes evolving into entities, 142-145 attributes of relationships, 134-136 case study, 162-164

database evolution, 141-142

derived or redundant relationship, 150-153 exercises, 160-161

mapping rules for recursive relationships, 158-159 methodology review, 156-158

more than two entities, 138-140 multiple relationships, 149-150 recursive relationships, 145-149

many-to-many recursive relationship, 149 one-to-many recursive relationship, 148-149 one-to-one recursive relationship, 147-148

relationships developing into entities, 136-138 attributes, 137

entity, 137 keys, 138

Index

C

Candidate key, 13, 14, 33, 37, 45, 96, 117, 138, 195, 206, 233

Cardinality expression of, 77 one-to-many, 6

ratio, 74, 75, 77, 154, 223, 233

Chen-like model, 46, 58, 63, 80, 85, 117, 153 Barker/Oracle-like model versus, 220 depiction of relationship in, 55, 78 derived attribute in, 33

foreign keys in, 226 multi-valued attributes in, 226 standard form of, 28

unique identifiers in, 34 use of weak entity in, 115

Composite attribute, 28-30, 31, 54, 95, 98, 125, 206, 220, 233 Conceptual model, 25, 77

Constraint(s) entity-integrity, 16 overlapping, 191

participation, 78, 208, 235 structural, 5, 54, 80, 166, 223, 235

definition of, 73

ER notation for specifying, 154 recursive relationships and, 147 ternary relationships, 169

weak entities and, 119

Index

D

Data

arrangement of in hierarchical fashion, 5 modeling schema, 24

models, 4

two-dimensional tables of, 8

Database, 8, 54, 82, 136, 138, 166, 175, 233 applications, 187

creation, 77 definitions, 25 design of, 4 evolution of, 141 mapped, 226 models, 5, 26 office, 193

query languages, 31 redundancy in, 208

relational, 1, 2, 13, 44, 69, 98, 162, 195, 198, 205, 210, 220 mapping of entity diagram to, 42

mapping of ternary diagrams to, 182 mapping of weak entities to, 125

requirements, 56, 196 semantic models in, 24 software, 7

specifying, 2 superclass in, 188 systems, modeling of, 3 texts, older, 76

Decomposition rule, 12 Degree of relationship, 55, 233

Derived attribute, 28-30, 33, 233 Derived relationship, 150

Index

E

EER model, see Enhanced Entity Relationship model Enhanced Entity Relationship (EER) model, 187, 188

Entity(ies), 233

attributes evolving into, 140, 142 change of attribute to, 54 definition, 25, 54

development of relationships into, 136 disjoint, 193

English description of, 36, 59 examination, 54

examples of, 25 identifying, 116 -integrity constraint, 16 intersection, 134, 228 -only ER diagram, 28 owner, 116

regular, 35, 235 sets, 25, 234

strong, 35, 96, 119, 136, 206, 234, 235 definition of, 145

mapping of attributes into, 43 weak entity connected to, 125

type, 234

weak, 35, 115, 178, 206, 213, 220, 225, 234, 236 definition of, 145

grammar, 124

identifying owner and, 119, 121 relationship, 189 reverse-engineering, 214 structural constraints and, 119 weak entities connected to, 121

Entity diagram, beyond first, 53-71 attribute versus relationship, 61-62 defining new entity relationship, 54-56 defining second entity, 58-60

entity examination, 54

ER design methodology, 56-57, 62 attribute information, 57, 62

connection of entities with relationships, 62 data, 57

examination of attributes, 62 sample data, 62

second entity, 62

selection of primary entity, 56, 62 use of structured English, 56, 62

exercises, 63-64

existence of relationship, 60-61 grammar for ER diagrams, 57

Entity relationship (ER), 3, 23 database systems modeled using, 3 design

methodology, 27, 37, 41 trap in, 77

model, 33, 178, 187

Entity relationship diagram (ERD), 4, 23-51 attributes, 28-35

composite attribute, 31-32 derived attribute, 33 keys, 33-35

multi-valued attribute, 32-33 simple or atomic attribute, 30-31

beginning methodology, 26-27 case study, 48-51

selection of primary entity, 48 use of structured English, 49-51

database definition, 25-26 data modeling schema, 24 definition of, 24-25

English description of entity, 36-37 attributes, 37 entity, 36

keys, 37

ER design methodology, 27, 37-42 data, 42

examples, 38-41 sample data, 37

selection of primary entity, 41 use of structured English, 37, 42

exercises, 46-47 first entity-only, 28 grammar for, 57

mapping of entity diagram to relational database, 42-46 models of, 219

ER, see Entity relationship

ERD, see Entity relationship diagram

Index

F

FD, see Functional dependency First normal form, 15, 234

Foreign key(s), 17, 182, 207, 211, 234 Chen-like model, 226

Oracle model, 227

Full participation, 78, 80, 131, 136, 234

Functional dependency (FD), 2, 140, 234 contradiction to known, 9

definition of, 8

inference, transitivity rule of, 10 left-hand side of, 9

rules, 14

sample data for, 9

Index

G

Generalization, 26, 209, 234

Generalizations and specializations, 187-203 case study, 200-203

definition, 188 example, 189-194 exercises, 198-199 mapping rules, 195-198

methodology and grammar, 194-195 problem with variants, 188-189

Glossary, 233-236