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PART 1 DATABASE SYSTEM ARCHITECTURE 3

CHAPTER 1 BASIC CONCEPTS 3

1.1 What Is a Database? 3

1.2 Why Database? 6

1.3 Data Independence 9

1.4 An Architecture for a Database System 13

Exercises 21

References and Bibliography 22

CHAPTER 2 STORAGE STRUCTURES 27

2.1 Introduction 27

2.2 Possible Representations for Some Sample Data 30

2.3 The Physical Record Irnerface: Intlexing Techniques 37

2.4 General Indexing Techniques 40

Exercises 43

References and Bibliography 44

CHAPTER 3 DATA MODELS AND DATA SUBLANGUAGES 51

3.1 Introduction 51

3.2 The Relational Approach 52

3.3 The Hierarchical Approach 55

3.4 The Network Approach 58

3.5 Higher-Level Data Sublanguages 62

3.6 Summary 66

Exercises 67

References and Bibliography 68

PART 2 THE RELATIONAL APPROACH 73

CHAPTER 4 THE RELATIONAL DATA MODEL 73

4.1 Relations 73

4.2 Domains and Attributes 75

4.3 Keys 77

4.4 Summary 79

Exercises 81

References and Bibliography 81

CHAPTER 5 A DATA SUBLANGUAGE BASED ON RELATIONAL CALCULUS 83

5.1 Introduction 83

5.2 Assumptions and Definitions 84

5.3 Retrieval Operations 86

5.4 Storage Operations 96

5.5 Library Functions 98

5.6 Summary 103

Exercises 104

References and Bibliography 107

CHAPTER 6 A DATA SUBLANGUAGE BASED ON RELATIONAL ALGEBRA 113

6.1 Introduction 113

6.2 Traditional Set Operations 114

6.3 Special Relational Operations 115

6.4 Retrieval Examples 118

6.5 Storage Examples 119

6.6 Summary 119

Exercises 120

References and Bibliography 120

CHAPTER 7 THE DATA SUBLANGUAGE SEQUEL 123

7.1 Introduction 123

7.2 Retrieval Operations 124

7.3 Storage Operations 131

7.4 Library Functions 132

7.5 Summary 134

Exercises 134

References and Bibliography 134

CHAPTER 8 QUERY BY EXAMPLE 137

8.1 Introduction 137

8.2 Retrieval Operations 138

8.3 Retrieval Operations on Tree-Structured Relations 143

8.4 Storage Operations 146

8.5 Library Functions 148

8.6 Retrieval Operations on the Dictionary 149

8.7 Summary 151

Exercises 152

References and Bibliography 152

CHAPTER 9 FURTHER NORMALIZATION 153

9.1 Introduction 153

9.2 Functional Dependence 154

9.3 First, Second,and Third Normal Forms 156

9.4 Relations With More Than One Candidate Key 163

9.5 Fourth Normal Form 167

9.6 Summary 169

Exercises 170

References and Bibliography 172

CHAPTER 10 THE EXTERNAL MODEL 179

10.1 Introduction 179

10.2 External Relations 180

10.3 External Domains 183

10.4 Data Sublanguage Operations 185

10.5 Changes to the Conceptual Schema 186

10.6 Summary 188

Exercises 190

References and Bibliography 190

CHAPTER 11 SOME RELATIONAL SYSTEMS 191

11.1 Introduction 191

11.2 Early Systems 191

11.3 Recent Systems 193

References and Bibliography 196

PART 3 THE HIERARCHICAL APPROACH 205

CHAPTER 12 THE ARACHTTECTURE OF AN IMS SYSTEM 205

12.1 Background 205

12.2 Architecture 206

References and Bibliography 208

CHAPTER 13 THE INS DATA MODEL 209

13.1 Physical Databases 209

13.2 The Database Description 212

13.3 Hierarchical Sequence 215

13.4 Some Remarks on the Education Datebase 216

Exercise 217

References and Bibliography 218

CHAPTER 14 THE IMS EXTERNAL MODEL 219

14.1 Logical Databases 219

14.2 The Program Communication Block 221

Exercise 223

References and Bibliography 223

CHAPTER15 THE IMS DATA SUBLANQUAGE 225

15.1 Defining the Program Communication Block （PCD） 225

15.2 The DL/I Operations 227

15.3 DL/I Examples 229

15.4 Constructing the Segment Search Angument （SSA） 234

15.5 SSA Command Codes 234

Exercises 239

References and Bibliography 239

CHAPTER 16 IMS STORAGE STRUCTURES 241

16.1 Introduction 241

16.2 HSAM 243

16.3 HISAM 244

16.4 HD Structures: Pointers 249

16.5 HDAM 251

16.6 HIDAM 254

16.7 Secondary Data Set Groups 255

16.8 The Mapping Definition 260

16.9 Reorganization 264

16.10 Data Independence 265

16.11 Summary 267

Exercises 268

References and Bibliography 268

CHAPTER 17 IMS LOGICAL DATABASES 269

17.1 Logical Databases （LDBs） 269

17.2 An Example 270

17.3 Termninology 273

17.4 The Database Deacriptions （DBDs） 274

17.5 Loading the Logicad Database 277

17.6 Processing the Logical Database 278

17.7 Bidirectional Logical Relationships 280

17.8 A Note on the Storage Structure 286

17.9 Logical Databases Involving a Single Physical Database 286

17.10 Some Rules and Restrictions 290

17.11 Summary 291

Exercises 291

References and Bibliography 292

CHAPTER 18 IMS SECONDARY INDEXING 293

18.1 Introduction 293

18.2 Indexing the Root on a Field Not the Sequence Field 295

18.3 Indexing the Root on a Field in a Dependent 298

18.4 Indexing a Dependent on a Field in That Dependent 301

18.5 Indexing a Dependent on a Field in a Lower-Level Dependent 303

18.6 Additronal Features 304

18.7 Summary 304

Exercises 306

References and Bibliography 306

PART 4 THE NETWORK APPROACH 309

CHAPTER 19 THE ARCHITECTURE OF A DBTG SYSTEM 309

19.1 Background 309

19.2 Architecture 311

References and Bibliography 313

CHAPTER 20 THE DBTG DATA MODEL 315

20.1 Introduction 315

20.2 The Set Construct: Hierarchical Examples 316

20.3 The Set Construct: Network Examples 323

20.4 Singular Sets 326

20.5 Areas 327

20.6 Database-Keys 328

20.7 A Sample Schema 329

20.8 Membership Class 335

20.9 LOCATION MODE 338

20.10 SET SELECTION 339

20.11 Source and Result Data-Items 343

20.12 DDL/COBOL Terminology 344

Exercises 345

References and Bibliography 346

CHAPTER 21 THE DBTG EXTERNAL MODEL 349

21.1 Introduction 349

21.2 Differences between the Sub-Schemaand Schema 349

21.3 A Sample Sub-Schema 351

Exercise 351

References and Bibliography 352

CHAPTER 22 THE DBTG DATA SUBLANGUAGE 353

22.1 Introduction 353

22.2 Currency 353

22.3 GET 356

22.4 MODIFY 357

22.5 CONNECT 359

22.6 DISCONNECT 359

22.7 ERASE 360

22.8 STORE 361

22.9 FIND 361

22.10 Miscellaneous Statements 368

Exercises 369

References and Bibliography 371

PART 5 SECURITY AND INTEGRITY 375

CHAPTER 23 SECURITY 375

23.1 Introduction 375

23.2 Identification and Authentication 377

23.3 Access Control 378

23.4 Security in IMS 385

23.5 Security in DBTG 386

23.6 Bypassing the System 388

Exercise 389

References and Bibliography 390

CHAPTER 24 INTEGRITY 395

24.1 Introduction 395

24.2 Integrity Constraints 396

24.3 Data Sharing 405

24.4 Support Routines 408

24.5 Integrity in IMS 410

24.6 Integrity in DBTG 412

References and Bibliography 418

PART 6 REVIEW, ANALYSIS, AND COMPARISONS 425

CHAPTER 25 THE THREE APPROACHES REVISITED 425

25.1 The ANSI/SPARC Architecture 425

25.2 The External Level 429

25.3 The Conceptual Level 443

25.4 Conclusion 456

References and Bibliography 457

Answers to Selected Exercises 463

Index 525