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Sybase 12.4.2 User Manual

Page 10

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Contents

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Referential integrity is unenforced......................................... 284

Integrity rules in the system tables ............................................... 285

CHAPTER 8

Transactions and Versioning ..................................................... 287

Overview of transactions and versioning ..................................... 287

Introduction to transactions ................................................... 287
Introduction to concurrency ................................................... 290
Introduction to versioning ...................................................... 291

Versioning prevents inconsistencies ............................................ 299
How locking works ....................................................................... 299

Locks for DML operations ..................................................... 299
Locks for DDL operations...................................................... 300
Primary keys and locking ...................................................... 302

Isolation levels.............................................................................. 302
Checkpoints, savepoints, and transaction rollback ...................... 303

Checkpoints........................................................................... 304
Savepoints within transactions .............................................. 305
Rolling back transactions ...................................................... 307
System recovery.................................................................... 307
How transaction information aids recovery ........................... 308

Performance implications ............................................................. 309

Overlapping versions and deletions ...................................... 310

Cursors in transactions ................................................................ 311

Cursors and versioning ......................................................... 312
Cursor sensitivity ................................................................... 312
Cursor scrolling ..................................................................... 312
Hold cursors .......................................................................... 313
Positioned operations............................................................ 313
Cursor command syntax and examples ................................ 313
Controlling message logging for cursors ............................... 313

CHAPTER 9

International Languages and Character Sets ........................... 315

Introduction to international languages and character sets.......... 315

Adaptive Server IQ international features ............................. 315
Using the default collation ..................................................... 316
Character set questions and answers ................................... 316

Understanding character sets in software.................................... 317

Pieces in the character set puzzle......................................... 317
Language issues in client/server computing ......................... 318
Code pages in Windows and Windows NT ........................... 319
Multibyte character sets ........................................................ 321
Sorting characters using collations........................................ 322
International aspects of case sensitivity ................................ 322