The SQL Guide to Pervasive PSQL - Danysoft

The SQL Guide to Pervasive PSQL Rick F. van der Lans

Copyright © 2009 by R20/Consultancy All rights reserved; no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form of by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim, the designations have been printed with initial capital letters or in all capitals. The author and publisher have taken care in the preparation of this book, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of the use of the information or programs contained herein. Author: Rick F. van der Lans Title: The SQL Guide to Pervasive PSQL First Lulu edition 2009 Uploaded October 09 ISBN: 978-0-557-10543-4 Published by Lulu www.lulu.com Edited by Diane Cools Book design by R20/Consultancy

Contents About the Author

xiii

Foreword by Nancy Woodward

xv

Preface

xvii

Part I

Introduction

23

1

Introduction to Pervasive PSQL

25 25 26 27 32 36 37 39 43 45

2

The Tennis Club Sample Database

47 47 47 50 53

3

Installing the Software

55 55 55 55 56 56 56

4

SQL in a Nutshell

57 57 57 59 61 62 64

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9

2.1 2.2 2.3 2.4

3.1 3.2 3.3 3.4 3.5 3.6

4.1 4.2 4.3 4.4 4.5 4.6

Introduction Database, Database Server, and Database Language The Relational Model What Is SQL? The History of SQL From Monolithic via Client/Server to the Internet Standardization of SQL The History of Pervasive PSQL The Structure of This Book

Introduction Description of the Tennis Club The Contents of the Tables Integrity Constraints

Introduction Downloading Pervasive PSQL Installation of Pervasive PSQL Installing a Query Tool Downloading SQL Statements from the Website Ready?

Introduction Creating Databases Creating New SQL Users Creating Tables Populating Tables with Data Querying Tables

vi | The SQL Guide to Pervasive PSQL

4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14

Updating and Deleting Rows Optimizing Query Processing with Indexes Views Users and Data Security Deleting Database Objects Grouping of SQL Statements The Catalog Tables Definitions of SQL Statements

66 68 69 70 71 71 72 80

Part II

Querying and Updating Data

83

5

SELECT Statement: Common Elements

85 85 86 94 97 99 100 101 106 106 110 113 114 125 125 126 126

6

SELECT Statements, Table Expressions, and Subqueries

131 131 131 135 140 143 143 149

7

SELECT Statement: the FROM Clause

153 153 153 154 155 158 159 162 165 165 169 176 179 179 187

5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 5.13 5.14 5.15 5.16

6.1 6.2 6.3 6.4 6.5 6.6 6.7

7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 7.12 7.13 7.14

Introduction Literals and their Data Types Expressions Assigning Names to Result Columns The Column Specification The System Variable The Case Expression The Scalar Expression Between Round Brackets The Scalar Function Casting of Expressions The Null Value as an Expression The Compound Scalar Expression The Aggregation Function and the Scalar Subquery The Row Expression The Table Expression Answers

Introduction The Definition of the SELECT Statement Processing the Clauses in a Select Block Possible Forms of a Table Expression What is a SELECT Statement? What is a Subquery? Answers

Introduction Table Specifications in the FROM Clause Again, the Column Specification Multiple Table Specifications in the FROM Clause Pseudonyms for Table Names Various Examples of Joins Mandatory Use of Pseudonyms Accessing Tables of Different Databases Explicit Joins in the FROM Clause Outer Joins Additional Conditions in the Join Condition The Cross Join The FROM Clause with Table Expressions Answers

Contents | vii

8

8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16

SELECT Statement: the WHERE Clause

193 193 194 198 201 203 206 208 214 216 218 220 223 230 234 239 242

Introduction Conditions Using Comparison Operators Comparison Operators with Subqueries Comparison Operators with Correlated Subqueries Conditions Coupled with AND, OR, and NOT The IN Operator with Expression List The IN Operator with Subquery The BETWEEN Operator The LIKE Operator The IS NULL Operator The EXISTS Operator The ALL and ANY Operators Scope of Columns in Subqueries More Examples with Correlated Subqueries Conditions with Negation Answers

9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11

Introduction Selecting All Columns (*) Expressions in the SELECT Clause Removing Duplicate Rows with DISTINCT When Are Two Rows Equal? An Introduction to Aggregation Functions COUNT Function MAX and MIN Functions SUM and AVG Functions The Top Specification Answers

SELECT Statement: SELECT Clause and Aggregation Functions

251 251 252 253 254 257 259 261 265 270 274 277

10

SELECT Statement: the GROUP BY Clause

281 281 282 285 287 289 289 292 297

11

SELECT Statement: the HAVING Clause

301 301 302 305 306

12

SELECT Statement: the ORDER BY Clause

309 309 310 311 313 315 317

9

10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8

11.1 11.2 11.3 11.4

12.1 12.2 12.3 12.4 12.5 12.6

Introduction Grouping on One Column Grouping on Two or More Columns Grouping on Expressions Grouping of Null Values General Rules for the GROUP BY Clause Complex Examples with GROUP BY Answers

Introduction Examples of the HAVING Clause General Rule for the HAVING Clause Answers

Introduction Sorting on Column Names Sorting on Expressions Sorting with Sequence Numbers Sorting in Ascending and Descending Order Sorting of Null Values

viii | The SQL Guide to Pervasive PSQL

12.7 12.8

Case Insensitive Sorting Answers

318 319

13

Combining Table Expressions

321 321 322 324 327 328 329

14

Updating Tables

Introduction Inserting New Rows Populating a Table with Rows from Another Table Updating Values in Rows Deleting Rows from a Table Answers

331 331 331 334 337 342 343

Part III

Creating Database Objects

345

15

Databases

347 347 348 350 352 353

16

Creating Tables

355 355 355 358 367 368 369 371 374 376

17

Integrity Constraints

379 379 381 383 385 389 391 391 392 392 393

13.1 13.2 13.3 13.4 13.5 13.6

14.1 14.2 14.3 14.4 14.5 14.6

15.1 15.2 15.3 15.4 15.5

16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9

17.1 17.2 17.3 17.4 17.5 17.6 17.7 17.8 17.9 17.10

Introduction Combining with UNION Rules for Using UNION Keeping Duplicate Rows with ALL Set Operators and the Null Value Answers

Introduction Creating Databases Retrieving and Changing Data on Databases Security of Databases Dropping Databases

Introduction Creating New Tables Data Types of Columns Creating Temporary Tables Naming Tables and Columns Default Value of a column Table Options Tables and the Catalog Answers

Introduction Primary Keys Alternate Keys Foreign Keys The Referencing Action Naming Integrity Constraints Non-modifiable Columns Deleting Integrity Constraints Integrity Constraints and the Catalog Answers

Contents | ix

18

Characters Sets and Collations

395 395 397 399 399 400

19

Changing and Dropping Tables

401 401 401 402 403 404 405 408 408 411 412 413 414 417

20

Storage Structures and Indexes

419 419 419 421 424 428 429 430 431 431 433 434 436 437 438 443 445 447

21

Views

449 449 449 453 454 455 456 456 457 460 464

18.1 18.2 18.3 18.4 18.5

19.1 19.2 19.3 19.4 19.5 19.6 19.7 19.8 19.9 19.10 19.11 19.12 19.13

20.1 20.2 20.3 20.4 20.5 20.6 20.7 20.8 20.9 20.10 20.11 20.12 20.13 20.14 20.15 20.16 20.17

21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 21.10

Introduction The Character Sets of Pervasive PSQL Assigning a Collation to a Column Sorting with Collations The SET DEFAULTCOLLATE statement

Introduction Removing Entire Tables Renaming Tables Changing Table Characteristics Adding Columns Moving Columns Renaming Columns Changing Columns Dropping Columns Adding Integrity Constraints Dropping Integrity Constraints Decoupling Tables from Files Answers

Introduction Rows, Tables, and Files How does an Index Work? Processing a SELECT statement: the Steps Creating Indexes Defining Partial Indexes Non-modifiable Indexes Decoupling Indexes from Files The Table Option LINKDUP Dropping Indexes Indexes and Primary Keys Indexes and Foreign Keys The Big PLAYERS_XXL Table Choosing columns for Indexes Hints, Indexes, and the Performance of Queries Indexes and the Catalog Answers

Introduction Creating Views The Column Names of Views Views and Privileges Deleting Views Views and the Catalog Restrictions on Changing the Contents of Views Processing View Statements Application Areas of Views Answers

x | The SQL Guide to Pervasive PSQL

22

Users and Data Security

Introduction Adding and Removing users Changing the Names of Users Changing Passwords Granting Table and Column Privileges Granting Database Privileges Assigning Users to Groups Recording Privileges in the Catalog Revoking Privileges Security of and through Views Protecting the Catalog Tables Answers

465 465 466 467 468 469 473 474 477 478 480 481 482

Part IV

Procedural Database Objects

483

23

Stored Procedures

485 485 486 490 491 493 495 496 502 505 509 511 514 516 521 523 525 527 527 528 528

22.1 22.2 22.3 22.4 22.5 22.6 22.7 22.8 22.9 22.10 22.11 22.12

23.1 23.2 23.3 23.4 23.5 23.6 23.7 23.8 23.9 23.10 23.11 23.12 23.13 23.14 23.15 23.16 23.17 23.18 23.19 23.20

Introduction An Example of a Stored Procedure The Parameters of a Stored Procedure The Body of a Stored Procedure Local Variables The SET Statement Flow Control Statements Calling Stored Procedures Querying Data with SELECT INTO Error Messages, SQLSTATE, and the SIGNAL Statement The BEGIN ATOMIC Statement A Set of Rows as Output Retrieving Data with a Cursor Updating and Deleting Data with a Cursor The Options of a Stored Procedure Stored Procedures and the Memory Cache Stored Procedures and the Catalog Removing Stored Procedures Security with Stored Procedures Advantages of Stored Procedures

24.1 24.2 24.3

Introduction Examples of Stored Functions Removing Stored Functions

Stored Functions

531 531 532 536

25

Triggers

537 537 538 540 545 547 548

24

25.1 25.2 25.3 25.4 25.5 25.6

Introduction An Example of a Trigger More Complex Examples Triggers and Integrity Constraints Removing Triggers Triggers and the Catalog

Contents | xi

Transaction and Multi-user Usage Introduction What is a Transaction? Starting of Transactions Savepoints Stored Procedures and Transactions Problems with Multi-user Usage Locking Deadlocks The Isolation Level Waiting for a Lock Answers

549 549 549 553 554 556 557 560 561 561 562 562

Appendices

565

A

Syntax of SQL

565

B

Scalar Functions

603

C

System Stored Procedures

623

D

Bibliography

633

Index

635

31

31.1 31.2 31.3 31.4 31.5 31.6 31.7 31.8 31.9 31.10 31.11