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| 129 | .\" ======================================================================== |
| 130 | .\" |
| 131 | .IX Title "DBI::FAQ 3" |
| 132 | .TH DBI::FAQ 3 "2002-10-01" "perl v5.8.0" "User Contributed Perl Documentation" |
| 133 | .SH "NAME" |
| 134 | DBI::FAQ \-\- The Frequently Asked Questions for the Perl5 Database Interface |
| 135 | .SH "SYNOPSIS" |
| 136 | .IX Header "SYNOPSIS" |
| 137 | .Vb 1 |
| 138 | \& perldoc DBI::FAQ |
| 139 | .Ve |
| 140 | .SH "VERSION" |
| 141 | .IX Header "VERSION" |
| 142 | This document is currently at version \fI0.38\fR, as of \fIFebruary 8th, 2000\fR. |
| 143 | .SH "DESCRIPTION" |
| 144 | .IX Header "DESCRIPTION" |
| 145 | This document serves to answer the most frequently asked questions on both |
| 146 | the \s-1DBI\s0 Mailing Lists and personally to members of the \s-1DBI\s0 development team. |
| 147 | .SH "Basic Information & Information Sources" |
| 148 | .IX Header "Basic Information & Information Sources" |
| 149 | .Sh "1.1 What is \s-1DBI\s0, DBperl, Oraperl and *perl?" |
| 150 | .IX Subsection "1.1 What is DBI, DBperl, Oraperl and *perl?" |
| 151 | To quote Tim Bunce, the architect and author of \s-1DBI:\s0 |
| 152 | .PP |
| 153 | .Vb 4 |
| 154 | \& ``DBI is a database access Application Programming Interface (API) |
| 155 | \& for the Perl Language. The DBI API Specification defines a set |
| 156 | \& of functions, variables and conventions that provide a consistent |
| 157 | \& database interface independant of the actual database being used.'' |
| 158 | .Ve |
| 159 | .PP |
| 160 | In simple language, the \s-1DBI\s0 interface allows users to access multiple database |
| 161 | types transparently. So, if you connecting to an Oracle, Informix, mSQL, Sybase |
| 162 | or whatever database, you don't need to know the underlying mechanics of the |
| 163 | 3GL layer. The \s-1API\s0 defined by \s-1DBI\s0 will work on \fIall\fR these database types. |
| 164 | .PP |
| 165 | A similar benefit is gained by the ability to connect to two \fIdifferent\fR |
| 166 | databases of different vendor within the one perl script, \fIie\fR, I want |
| 167 | to read data from an Oracle database and insert it back into an Informix |
| 168 | database all within one program. The \s-1DBI\s0 layer allows you to do this simply |
| 169 | and powerfully. |
| 170 | .PP |
| 171 | \&\fIDBperl\fR is the old name for the interface specification. It's usually |
| 172 | now used to denote perl\fI4\fR modules on database interfacing, such as, |
| 173 | \&\fIoraperl\fR, \fIisqlperl\fR, \fIingperl\fR and so on. These interfaces |
| 174 | didn't have a standard \s-1API\s0 and are generally \fInot\fR supported. |
| 175 | .PP |
| 176 | Here's a list of DBperl modules, their corresponding \s-1DBI\s0 counterparts and |
| 177 | support information. \fIPlease note\fR, the author's listed here generally |
| 178 | \&\fIdo not\fR maintain the \s-1DBI\s0 module for the same database. These email |
| 179 | addresses are unverified and should only be used for queries concerning the |
| 180 | perl4 modules listed below. \s-1DBI\s0 driver queries should be directed to the |
| 181 | \&\fIdbi-users\fR mailing list. |
| 182 | .PP |
| 183 | .Vb 23 |
| 184 | \& Module Name Database Required Author DBI |
| 185 | \& ----------- ----------------- ------ --- |
| 186 | \& Sybperl Sybase Michael Peppler DBD::Sybase |
| 187 | \& <mpeppler@itf.ch> |
| 188 | \& Oraperl Oracle 6 & 7 Kevin Stock DBD::Oracle |
| 189 | \& <dbi-users@perl.org> |
| 190 | \& Ingperl Ingres Tim Bunce & DBD::Ingres |
| 191 | \& Ted Lemon |
| 192 | \& <dbi-users@perl.org> |
| 193 | \& Interperl Interbase Buzz Moschetti DBD::Interbase |
| 194 | \& <buzz@bear.com> |
| 195 | \& Uniperl Unify 5.0 Rick Wargo None |
| 196 | \& <rickers@coe.drexel.edu> |
| 197 | \& Pgperl Postgres Igor Metz DBD::Pg |
| 198 | \& <metz@iam.unibe.ch> |
| 199 | \& Btreeperl NDBM John Conover SDBM? |
| 200 | \& <john@johncon.com> |
| 201 | \& Ctreeperl C-Tree John Conover None |
| 202 | \& <john@johncon.com> |
| 203 | \& Cisamperl Informix C-ISAM Mathias Koerber None |
| 204 | \& <mathias@unicorn.swi.com.sg> |
| 205 | \& Duaperl X.500 Directory Eric Douglas None |
| 206 | \& User Agent |
| 207 | .Ve |
| 208 | .PP |
| 209 | However, some \s-1DBI\s0 modules have DBperl emulation layers, so, \fIDBD::Oracle\fR |
| 210 | comes with an Oraperl emulation layer, which allows you to run legacy oraperl |
| 211 | scripts without modification. The emulation layer translates the oraperl \s-1API\s0 |
| 212 | calls into \s-1DBI\s0 calls and executes them through the \s-1DBI\s0 switch. |
| 213 | .PP |
| 214 | Here's a table of emulation layer information: |
| 215 | .PP |
| 216 | .Vb 8 |
| 217 | \& Module Emulation Layer Status |
| 218 | \& ------ --------------- ------ |
| 219 | \& DBD::Oracle Oraperl Complete |
| 220 | \& DBD::Informix Isqlperl Under development |
| 221 | \& DBD::Ingres Ingperl Complete? |
| 222 | \& DBD::Sybase Sybperl Working? ( Needs verification ) |
| 223 | \& DBD::mSQL Msqlperl Experimentally released with |
| 224 | \& DBD::mSQL-0.61 |
| 225 | .Ve |
| 226 | .PP |
| 227 | The \fIMsqlperl\fR emulation is a special case. \fIMsqlperl\fR is a perl5 driver |
| 228 | for \fImSQL\fR databases, but does not conform to the \s-1DBI\s0 Specification. It's |
| 229 | use is being deprecated in favour of \fIDBD::mSQL\fR. \fIMsqlperl\fR may be downloaded |
| 230 | from \s-1CPAN\s0 \fIvia\fR: |
| 231 | .PP |
| 232 | .Vb 1 |
| 233 | \& http://www.perl.com/cgi-bin/cpan_mod?module=Msqlperl |
| 234 | .Ve |
| 235 | .Sh "1.2. Where can I get it from?" |
| 236 | .IX Subsection "1.2. Where can I get it from?" |
| 237 | The Comprehensive Perl Archive Network |
| 238 | resources should be used for retrieving up-to-date versions of the \s-1DBI\s0 |
| 239 | and drivers. \s-1CPAN\s0 may be accessed \fIvia\fR Tom Christiansen's splendid |
| 240 | \&\fI\s-1CPAN\s0 multiplexer\fR program located at: |
| 241 | .PP |
| 242 | .Vb 1 |
| 243 | \& http://www.perl.com/CPAN/ |
| 244 | .Ve |
| 245 | .PP |
| 246 | For more specific version information and exact URLs of drivers, please see |
| 247 | the \s-1DBI\s0 drivers list and the \s-1DBI\s0 module pages which can be found on: |
| 248 | .PP |
| 249 | .Vb 2 |
| 250 | \& http://dbi.perl.org/ |
| 251 | \& http://www.symbolstone.org/technology/perl/DBI |
| 252 | .Ve |
| 253 | .PP |
| 254 | This list is automatically generated on a nightly basis from \s-1CPAN\s0 and should |
| 255 | be up\-to\-date. |
| 256 | .Sh "1.3. Where can I get more information?" |
| 257 | .IX Subsection "1.3. Where can I get more information?" |
| 258 | There are a few information sources on \s-1DBI\s0. |
| 259 | .ie n .IP "\fI""Programming the Perl \s-1DBI\s0""\fR" 4 |
| 260 | .el .IP "\fI``Programming the Perl \s-1DBI\s0''\fR" 4 |
| 261 | .IX Item "Programming the Perl DBI" |
| 262 | \&\*(L"Programming the Perl \s-1DBI\s0\*(R" is the \fIofficial\fR book on the \s-1DBI\s0 written by |
| 263 | Alligator Descartes and Tim Bunce and published by O'Reilly & Associates. |
| 264 | The book was released on February 9th, 2000. |
| 265 | .Sp |
| 266 | The table of contents is: |
| 267 | .Sp |
| 268 | .Vb 56 |
| 269 | \& Preface |
| 270 | \& 1. Introduction |
| 271 | \& From Mainframes to Workstations |
| 272 | \& Perl |
| 273 | \& DBI in the Real World |
| 274 | \& A Historical Interlude and Standing Stones |
| 275 | \& 2. Basic Non-DBI Databases |
| 276 | \& Storage Managers and Layers |
| 277 | \& Query Languages and Data Functions |
| 278 | \& Standing Stones and the Sample Database |
| 279 | \& Flat-File Databases |
| 280 | \& Putting Complex Data into Flat Files |
| 281 | \& Concurrent Database Access and Locking |
| 282 | \& DBM Files and the Berkeley Database Manager |
| 283 | \& The MLDBM Module |
| 284 | \& Summary |
| 285 | \& 3. SQL and Relational Databases |
| 286 | \& The Relational Database Methodology |
| 287 | \& Datatypes and NULL Values |
| 288 | \& Querying Data |
| 289 | \& Modifying Data Within Tables |
| 290 | \& Creating and Destroying Tables |
| 291 | \& 4. Programming with the DBI |
| 292 | \& DBI Architecture |
| 293 | \& Handles |
| 294 | \& Data Source Names |
| 295 | \& Connection and Disconnection |
| 296 | \& Error Handling |
| 297 | \& Utility Methods and Functions |
| 298 | \& 5. Interacting with the Database |
| 299 | \& Issuing Simple Queries |
| 300 | \& Executing Non-SELECT Statements |
| 301 | \& Binding Parameters to Statements |
| 302 | \& Binding Output Columns |
| 303 | \& do() Versus prepare() |
| 304 | \& Atomic and Batch Fetching |
| 305 | \& 6. Advanced DBI |
| 306 | \& Handle Attributes and Metadata |
| 307 | \& Handling LONG/LOB Data |
| 308 | \& Transactions, Locking, and Isolation |
| 309 | \& 7. ODBC and the DBI |
| 310 | \& ODBC -- Embraced and Extended |
| 311 | \& DBI -- Thrashed and Mutated |
| 312 | \& The Nuts and Bolts of ODBC |
| 313 | \& ODBC from Perl |
| 314 | \& The Marriage of DBI and ODBC |
| 315 | \& Questions and Choices |
| 316 | \& Moving Between Win32::ODBC and the DBI |
| 317 | \& And What About ADO? |
| 318 | \& 8. DBI Shell and Database Proxying |
| 319 | \& dbish -- The DBI Shell |
| 320 | \& Database Proxying |
| 321 | \& A. DBI Specification |
| 322 | \& B. Driver and Database Characteristics |
| 323 | \& C. ASLaN Sacred Site Charter |
| 324 | \& Index |
| 325 | .Ve |
| 326 | .Sp |
| 327 | The book should be available from all good bookshops and can be ordered online |
| 328 | either <I>via</I> O'Reilly & Associates |
| 329 | .Sp |
| 330 | .Vb 1 |
| 331 | \& http://www.oreilly.com/catalog/perldbi |
| 332 | .Ve |
| 333 | .Sp |
| 334 | or Amazon |
| 335 | .Sp |
| 336 | .Vb 1 |
| 337 | \& http://www.amazon.com/exec/obidos/ASIN/1565926994/dbi |
| 338 | .Ve |
| 339 | .IP "\fI\s-1POD\s0 documentation\fR" 4 |
| 340 | .IX Item "POD documentation" |
| 341 | \&\fI\s-1POD\s0\fRs are chunks of documentation usually embedded within perl programs |
| 342 | that document the code ``\fIin place\fR'', providing a useful resource for |
| 343 | programmers and users of modules. \s-1POD\s0 for \s-1DBI\s0 and drivers is beginning to |
| 344 | become more commonplace, and documentation for these modules can be read |
| 345 | with the \f(CW\*(C`perldoc\*(C'\fR program included with Perl. |
| 346 | .RS 4 |
| 347 | .IP "The \s-1DBI\s0 Specification" 4 |
| 348 | .IX Item "The DBI Specification" |
| 349 | The \s-1POD\s0 for the \s-1DBI\s0 Specification can be read with the: |
| 350 | .Sp |
| 351 | .Vb 1 |
| 352 | \& perldoc DBI |
| 353 | .Ve |
| 354 | .Sp |
| 355 | command. The Specification also forms Appendix A of \*(L"Programming the Perl |
| 356 | \&\s-1DBI\s0\*(R". |
| 357 | .IP "Oraperl" 4 |
| 358 | .IX Item "Oraperl" |
| 359 | Users of the Oraperl emulation layer bundled with \fIDBD::Oracle\fR, may read |
| 360 | up on how to program with the Oraperl interface by typing: |
| 361 | .Sp |
| 362 | .Vb 1 |
| 363 | \& perldoc Oraperl |
| 364 | .Ve |
| 365 | .Sp |
| 366 | This will produce an updated copy of the original oraperl man page written by |
| 367 | Kevin Stock for perl4. The oraperl \s-1API\s0 is fully listed and described there. |
| 368 | .IP "Drivers" 4 |
| 369 | .IX Item "Drivers" |
| 370 | Users of the \s-1DBD\s0 modules may read about some of the private functions |
| 371 | and quirks of that driver by typing: |
| 372 | .Sp |
| 373 | .Vb 1 |
| 374 | \& perldoc <driver> |
| 375 | .Ve |
| 376 | .Sp |
| 377 | For example, the \fIDBD::mSQL\fR driver is bundled with driver-specific |
| 378 | documentation that can be accessed by typing |
| 379 | .Sp |
| 380 | .Vb 1 |
| 381 | \& perldoc DBD::mSQL |
| 382 | .Ve |
| 383 | .IP "Frequently Asked Questions" 4 |
| 384 | .IX Item "Frequently Asked Questions" |
| 385 | This document, the \fIFrequently Asked Questions\fR is also available as \s-1POD\s0 |
| 386 | documentation! You can read this on your own system by typing: |
| 387 | .Sp |
| 388 | .Vb 1 |
| 389 | \& perldoc DBI::FAQ |
| 390 | .Ve |
| 391 | .Sp |
| 392 | This may be more convenient to persons not permanently, or conveniently, |
| 393 | connected to the Internet. The \fI\s-1DBI::FAQ\s0\fR module should be downloaded and |
| 394 | installed for the more up-to-date version. |
| 395 | .Sp |
| 396 | The version of \fI\s-1DBI::FAQ\s0\fR shipped with the \f(CW\*(C`DBI\*(C'\fR module may be slightly out |
| 397 | of date. |
| 398 | .IP "\s-1POD\s0 in general" 4 |
| 399 | .IX Item "POD in general" |
| 400 | Information on writing \s-1POD\s0, and on the philosophy of \s-1POD\s0 in general, can be |
| 401 | read by typing: |
| 402 | .Sp |
| 403 | .Vb 1 |
| 404 | \& perldoc perlpod |
| 405 | .Ve |
| 406 | .Sp |
| 407 | Users with the Tk module installed may be interested to learn there is a |
| 408 | Tk-based \s-1POD\s0 reader available called \f(CW\*(C`tkpod\*(C'\fR, which formats \s-1POD\s0 in a convenient |
| 409 | and readable way. This is available \fIvia\fR \s-1CPAN\s0 as the module called |
| 410 | \&\fITk::POD\fR and is highly recommended. |
| 411 | .RE |
| 412 | .RS 4 |
| 413 | .RE |
| 414 | .IP "\fIDriver and Database Characteristics\fR" 4 |
| 415 | .IX Item "Driver and Database Characteristics" |
| 416 | The driver summaries that were produced for Appendix B of \*(L"Programming the |
| 417 | Perl \s-1DBI\s0\*(R" are available online at: |
| 418 | .Sp |
| 419 | .Vb 2 |
| 420 | \& http://dbi.perl.org/ |
| 421 | \& http://www.symbolstone.org/technology/perl/DBI |
| 422 | .Ve |
| 423 | .Sp |
| 424 | in the driver information table. These summaries contain standardised |
| 425 | information on each driver and database which should aid you in selecting |
| 426 | a database to use. It will also inform you quickly of any issues within |
| 427 | drivers or whether a driver is not fully compliant with the \s-1DBI\s0 Specification. |
| 428 | .IP "\fIRambles, Tidbits and Observations\fR" 4 |
| 429 | .IX Item "Rambles, Tidbits and Observations" |
| 430 | .Vb 2 |
| 431 | \& http://dbi.perl.org/tidbits |
| 432 | \& http://www.symbolstone.org/technology/perl/DBI/tidbits |
| 433 | .Ve |
| 434 | .Sp |
| 435 | There are a series of occasional rambles from various people on the |
| 436 | \&\s-1DBI\s0 mailing lists who, in an attempt to clear up a simple point, end up |
| 437 | drafting fairly comprehensive documents. These are quite often varying in |
| 438 | quality, but do provide some insights into the workings of the interfaces. |
| 439 | .IP "\fIArticles\fR" 4 |
| 440 | .IX Item "Articles" |
| 441 | A list of articles discussing the \s-1DBI\s0 can be found on the \s-1DBI\s0 \s-1WWW\s0 page at: |
| 442 | .Sp |
| 443 | .Vb 2 |
| 444 | \& http://dbi.perl.org/ |
| 445 | \& http://www.symbolstone.org/technology/perl/DBI |
| 446 | .Ve |
| 447 | .Sp |
| 448 | These articles are of varying quality and age, from the original Perl Journal |
| 449 | article written by Alligator and Tim, to more recent debacles published online |
| 450 | from about.com. |
| 451 | .IP "\fI\s-1README\s0 files\fR" 4 |
| 452 | .IX Item "README files" |
| 453 | The \fI\s-1README\s0\fR files included with each driver occasionally contains |
| 454 | some useful information ( no, really! ) that may be pertinent to the user. |
| 455 | Please read them. It makes our worthless existences more bearable. These |
| 456 | can all be read from the main \s-1DBI\s0 \s-1WWW\s0 page at: |
| 457 | .Sp |
| 458 | .Vb 2 |
| 459 | \& http://dbi.perl.org/ |
| 460 | \& http://www.symbolstone.org/technology/perl/DBI |
| 461 | .Ve |
| 462 | .IP "\fIMailing Lists\fR" 4 |
| 463 | .IX Item "Mailing Lists" |
| 464 | There are three mailing lists for \s-1DBI:\s0 |
| 465 | .Sp |
| 466 | .Vb 3 |
| 467 | \& dbi-announce@perl.org -- for announcements, very low traffic |
| 468 | \& dbi-users@perl.org -- general user support |
| 469 | \& dbi-dev@perl.org -- for driver developers (no user support) |
| 470 | .Ve |
| 471 | .Sp |
| 472 | For information on how to subscribe, set digest mode etc, and unsubscribe, |
| 473 | send an email message (the content will be ignored) to: |
| 474 | .Sp |
| 475 | .Vb 3 |
| 476 | \& dbi-announce-help@perl.org |
| 477 | \& dbi-users-help@perl.org |
| 478 | \& dbi-dev-help@perl.org |
| 479 | .Ve |
| 480 | .IP "\fIMailing List Archives\fR" 4 |
| 481 | .IX Item "Mailing List Archives" |
| 482 | .RS 4 |
| 483 | .PD 0 |
| 484 | .IP "\fI\s-1US\s0 Mailing List Archives\fR" 4 |
| 485 | .IX Item "US Mailing List Archives" |
| 486 | .PD |
| 487 | .Vb 1 |
| 488 | \& http://outside.organic.com/mail-archives/dbi-users/ |
| 489 | .Ve |
| 490 | .Sp |
| 491 | Searchable hypermail archives of the three mailing lists, and some of the |
| 492 | much older traffic have been set up for users to browse. |
| 493 | .IP "\fIEuropean Mailing List Archives\fR" 4 |
| 494 | .IX Item "European Mailing List Archives" |
| 495 | .Vb 1 |
| 496 | \& http://www.rosat.mpe-garching.mpg.de/mailing-lists/PerlDB-Interest |
| 497 | .Ve |
| 498 | .Sp |
| 499 | As per the \s-1US\s0 archive above. |
| 500 | .RE |
| 501 | .RS 4 |
| 502 | .RE |
| 503 | .SH "Compilation Problems" |
| 504 | .IX Header "Compilation Problems" |
| 505 | .ie n .Sh "2.1. Compilation problems or ""It fails the test!""" |
| 506 | .el .Sh "2.1. Compilation problems or ``It fails the test!''" |
| 507 | .IX Subsection "2.1. Compilation problems or It fails the test!" |
| 508 | First off, consult the \s-1README\s0 for that driver in case there is useful |
| 509 | information about the problem. It may be a known problem for your given |
| 510 | architecture and operating system or database. You can check the \s-1README\s0 |
| 511 | files for each driver in advance online at: |
| 512 | .PP |
| 513 | .Vb 2 |
| 514 | \& http://dbi.perl.org/ |
| 515 | \& http://www.symbolstone.org/technology/perl/DBI |
| 516 | .Ve |
| 517 | .PP |
| 518 | If it's a known problem, you'll probably have to wait till it gets fixed. If |
| 519 | you're \fIreally\fR needing it fixed, try the following: |
| 520 | .IP "\fIAttempt to fix it yourself\fR" 4 |
| 521 | .IX Item "Attempt to fix it yourself" |
| 522 | This technique is generally \fInot\fR recommended to the faint\-hearted. |
| 523 | If you do think you have managed to fix it, then, send a patch file |
| 524 | ( context diff ) to the author with an explanation of: |
| 525 | .RS 4 |
| 526 | .IP "\(bu" 4 |
| 527 | What the problem was, and test cases, if possible. |
| 528 | .IP "\(bu" 4 |
| 529 | What you needed to do to fix it. Please make sure you mention everything. |
| 530 | .IP "\(bu" 4 |
| 531 | Platform information, database version, perl version, module version and |
| 532 | \&\s-1DBI\s0 version. |
| 533 | .RE |
| 534 | .RS 4 |
| 535 | .RE |
| 536 | .IP "\fIEmail the author\fR Do \fI\s-1NOT\s0\fR whinge!" 4 |
| 537 | .IX Item "Email the author Do NOT whinge!" |
| 538 | Please email the address listed in the \s-1WWW\s0 pages for whichever driver you |
| 539 | are having problems with. Do \fInot\fR directly email the author at a |
| 540 | known address unless it corresponds with the one listed. |
| 541 | .Sp |
| 542 | We tend to have real jobs to do, and we do read the mailing lists for |
| 543 | problems. Besides, we may not have access to <\fIinsert your |
| 544 | favourite brain-damaged platform here\fR> and couldn't be of any |
| 545 | assistance anyway! Apologies for sounding harsh, but that's the way of it! |
| 546 | .Sp |
| 547 | However, you might catch one of these creative genii at 3am when we're |
| 548 | doing this sort of stuff anyway, and get a patch within 5 minutes. The |
| 549 | atmosphere in the \s-1DBI\s0 circle is that we \fIdo\fR appreciate the users' |
| 550 | problems, since we work in similar environments. |
| 551 | .Sp |
| 552 | If you are planning to email the author, please furnish as much information |
| 553 | as possible, \fIie\fR: |
| 554 | .RS 4 |
| 555 | .IP "\(bu" 4 |
| 556 | \&\fI\s-1ALL\s0\fR the information asked for in the \s-1README\s0 file in |
| 557 | the problematic module. And we mean \fI\s-1ALL\s0\fR of it. We don't |
| 558 | put lines like that in documentation for the good of our health, or |
| 559 | to meet obscure \s-1README\s0 file standards of length. |
| 560 | .IP "\(bu" 4 |
| 561 | If you have a core dump, try the \fIDevel::CoreStack\fR module for |
| 562 | generating a stack trace from the core dump. Send us that too. |
| 563 | \&\fIDevel::CoreStack\fR can be found on \s-1CPAN\s0 at: |
| 564 | .Sp |
| 565 | .Vb 1 |
| 566 | \& http://www.perl.com/cgi-bin/cpan_mod?module=Devel::CoreStack |
| 567 | .Ve |
| 568 | .IP "\(bu" 4 |
| 569 | Module versions, perl version, test cases, operating system versions |
| 570 | and \fIany other pertinent information\fR. |
| 571 | .RE |
| 572 | .RS 4 |
| 573 | .Sp |
| 574 | Remember, the more information you send us, the quicker we can track |
| 575 | problems down. If you send us no useful information, expect nothing back. |
| 576 | .Sp |
| 577 | Finally, please be aware that some authors, including Tim Bunce, specifically |
| 578 | request that you do \fInot\fR mail them directly. Please respect their wishes and |
| 579 | use the email addresses listed in the appropriate module \f(CW\*(C`README\*(C'\fR file. |
| 580 | .RE |
| 581 | .IP "\fIEmail the dbi-users Mailing List\fR" 4 |
| 582 | .IX Item "Email the dbi-users Mailing List" |
| 583 | It's usually a fairly intelligent idea to \fIcc\fR the mailing list |
| 584 | anyway with problems. The authors all read the lists, so you lose nothing |
| 585 | by mailing there. |
| 586 | .SH "Platform and Driver Issues" |
| 587 | .IX Header "Platform and Driver Issues" |
| 588 | .Sh "3.1 What's the difference between \s-1ODBC\s0 and \s-1DBI\s0?" |
| 589 | .IX Subsection "3.1 What's the difference between ODBC and DBI?" |
| 590 | In terms of architecture \- not much: Both define programming |
| 591 | interfaces. Both allow multiple drivers to be loaded to do the |
| 592 | actual work. |
| 593 | .PP |
| 594 | In terms of ease of use \- much: The \s-1DBI\s0 is a 'high level' interface |
| 595 | that, like Perl itself, strives to make the simple things easy while |
| 596 | still making the hard things possible. The \s-1ODBC\s0 is a 'low level' |
| 597 | interface. All nuts\-bolts\-knobs\-and\-dials. |
| 598 | .PP |
| 599 | Now there's an \s-1ODBC\s0 driver for the \s-1DBI\s0 (\s-1DBD::ODBC\s0) the \*(L"What's the |
| 600 | difference\*(R" question is more usefully rephrased as: |
| 601 | .PP |
| 602 | Chapter 7 of \*(L"Programming the Perl \s-1DBI\s0\*(R" covers this topic in far more |
| 603 | detail and should be consulted. |
| 604 | .Sh "3.2 What's the difference between Win32::ODBC and \s-1DBD::ODBC\s0?" |
| 605 | .IX Subsection "3.2 What's the difference between Win32::ODBC and DBD::ODBC?" |
| 606 | The \s-1DBI\s0, and thus \s-1DBD::ODBC\s0, has a different philosophy from the |
| 607 | Win32::ODBC module: |
| 608 | .PP |
| 609 | The Win32::ODBC module is a 'thin' layer over the low-level \s-1ODBC\s0 \s-1API\s0. |
| 610 | The \s-1DBI\s0 defines a simpler 'higher level' interface. |
| 611 | .PP |
| 612 | The Win32::ODBC module gives you access to more of the \s-1ODBC\s0 \s-1API\s0. |
| 613 | The \s-1DBI\s0 and \s-1DBD::ODBC\s0 give you access to only the essentials. |
| 614 | (But, unlike Win32::ODBC, the \s-1DBI\s0 and \s-1DBD::ODBC\s0 do support parameter |
| 615 | binding and multiple prepared statements which reduces the load on |
| 616 | the database server and can dramatically increase performance.) |
| 617 | .PP |
| 618 | The Win32::ODBC module only works on Win32 systems. |
| 619 | The \s-1DBI\s0 and \s-1DBD::ODBC\s0 are very portable and work on Win32 and Unix. |
| 620 | .PP |
| 621 | The \s-1DBI\s0 and \s-1DBD::ODBC\s0 modules are supplied as a standard part of the |
| 622 | Perl 5.004 binary distribution for Win32 (they don't work with the |
| 623 | older, non\-standard, ActiveState port). |
| 624 | .PP |
| 625 | Scripts written with the \s-1DBI\s0 and \s-1DBD::ODBC\s0 are faster than Win32::ODBC |
| 626 | on Win32 and are trivially portable to other supported database types. |
| 627 | .PP |
| 628 | The \s-1DBI\s0 offers optional automatic printing or \fIdie()\fRing on errors which |
| 629 | makes applications simpler and more robust. |
| 630 | .PP |
| 631 | The current \s-1DBD::ODBC\s0 driver version 0.16 is new and not yet fully stable. |
| 632 | A new release is due soon [relative to the date of the next \s-1TPJ\s0 issue :\-] |
| 633 | and will be much improved and offer more \s-1ODBC\s0 functionality. |
| 634 | .PP |
| 635 | To summarise: The Win32::ODBC module is your best choice if you need |
| 636 | access to more of the \s-1ODBC\s0 \s-1API\s0 than the \s-1DBI\s0 gives you. Otherwise, the |
| 637 | \&\s-1DBI\s0 and \s-1DBD::ODBC\s0 combination may be your best bet. |
| 638 | .PP |
| 639 | Chapter 7 of \*(L"Programming the Perl \s-1DBI\s0\*(R" covers this topic in far more |
| 640 | detail and should be consulted. |
| 641 | .Sh "3.3 Is \s-1DBI\s0 supported under Windows 95 / \s-1NT\s0 platforms?" |
| 642 | .IX Subsection "3.3 Is DBI supported under Windows 95 / NT platforms?" |
| 643 | Finally, yes! Jeff Urlwin has been working diligently on building |
| 644 | \&\fI\s-1DBI\s0\fR and \fI\s-1DBD::ODBC\s0\fR under these platforms, and, with the |
| 645 | advent of a stabler perl and a port of \fIMakeMaker\fR, the project has |
| 646 | come on by great leaps and bounds. |
| 647 | .PP |
| 648 | The \fI\s-1DBI\s0\fR and \fIDBD::Oracle\fR Win32 ports are now a standard part of \s-1DBI\s0, |
| 649 | so, downloading \fI\s-1DBI\s0\fR of version higher than \fI0.81\fR should work fine as |
| 650 | should using the most recent \fIDBD::Oracle\fR version. |
| 651 | .Sh "3.4 Can I access Microsoft Access or SQL-Server databases with \s-1DBI\s0?" |
| 652 | .IX Subsection "3.4 Can I access Microsoft Access or SQL-Server databases with DBI?" |
| 653 | Yes, use the \fI\s-1DBD::ODBC\s0\fR driver. |
| 654 | .Sh "3.5 Is the a \s-1DBD\s0 for <\fIinsert favourite database here\fP>?" |
| 655 | .IX Subsection "3.5 Is the a DBD for <insert favourite database here>?" |
| 656 | Is is listed on the \s-1DBI\s0 drivers page? |
| 657 | .PP |
| 658 | .Vb 2 |
| 659 | \& http://dbi.perl.org/ |
| 660 | \& http://www.symbolstone.org/technology/perl/DBI |
| 661 | .Ve |
| 662 | .PP |
| 663 | If not, no. A complete absence of a given database driver from that |
| 664 | page means that no-one has announced any intention to work on it, not that |
| 665 | such a driver is impossible to write. |
| 666 | .PP |
| 667 | A corollary of the above statement implies that if you see an announcement |
| 668 | for a driver \fInot\fR on the above page, there's a good chance it's not |
| 669 | actually a \fI\s-1DBI\s0\fR driver, and may not conform to the specifications. Therefore, |
| 670 | questions concerning problems with that code should \fInot\fR really be addressed |
| 671 | to the \s-1DBI\s0 Mailing Lists. |
| 672 | .Sh "3.6 What's \s-1DBM\s0? And why should I use \s-1DBI\s0 instead?" |
| 673 | .IX Subsection "3.6 What's DBM? And why should I use DBI instead?" |
| 674 | Extracted from ``\fI\s-1DBI\s0 \- The Database Interface for Perl 5\fR'': |
| 675 | .PP |
| 676 | .Vb 3 |
| 677 | \& ``UNIX was originally blessed with simple file-based ``databases'', namely |
| 678 | \& the dbm system. dbm lets you store data in files, and retrieve |
| 679 | \& that data quickly. However, it also has serious drawbacks. |
| 680 | .Ve |
| 681 | .PP |
| 682 | .Vb 1 |
| 683 | \& File Locking |
| 684 | .Ve |
| 685 | .PP |
| 686 | .Vb 3 |
| 687 | \& The dbm systems did not allow particularly robust file locking |
| 688 | \& capabilities, nor any capability for correcting problems arising through |
| 689 | \& simultaneous writes [ to the database ]. |
| 690 | .Ve |
| 691 | .PP |
| 692 | .Vb 1 |
| 693 | \& Arbitrary Data Structures |
| 694 | .Ve |
| 695 | .PP |
| 696 | .Vb 4 |
| 697 | \& The dbm systems only allows a single fixed data structure: |
| 698 | \& key-value pairs. That value could be a complex object, such as a |
| 699 | \& [ C ] struct, but the key had to be unique. This was a large |
| 700 | \& limitation on the usefulness of dbm systems. |
| 701 | .Ve |
| 702 | .PP |
| 703 | .Vb 5 |
| 704 | \& However, dbm systems still provide a useful function for users with |
| 705 | \& simple datasets and limited resources, since they are fast, robust and |
| 706 | \& extremely well-tested. Perl modules to access dbm systems have now |
| 707 | \& been integrated into the core Perl distribution via the |
| 708 | \& AnyDBM_File module.'' |
| 709 | .Ve |
| 710 | .PP |
| 711 | To sum up, \s-1DBM\s0 is a perfectly satisfactory solution for essentially read-only |
| 712 | databases, or small and simple datasets. However, for more |
| 713 | scaleable dataset handling, not to mention robust transactional locking, |
| 714 | users are recommended to use a more powerful database engine \fIvia\fR \fI\s-1DBI\s0\fR. |
| 715 | .PP |
| 716 | Chapter 2 of \*(L"Programming the Perl \s-1DBI\s0\*(R" discusses \s-1DBM\s0 files in detail. |
| 717 | .Sh "3.7 What database do you recommend me using?" |
| 718 | .IX Subsection "3.7 What database do you recommend me using?" |
| 719 | This is a particularly thorny area in which an objective answer is difficult |
| 720 | to come by, since each dataset, proposed usage and system configuration |
| 721 | differs from person to person. |
| 722 | .PP |
| 723 | From the current author's point of view, if the dataset is relatively |
| 724 | small, being tables of less than 1 million rows, and less than 1000 tables |
| 725 | in a given database, then \fImSQL\fR is a perfectly acceptable solution |
| 726 | to your problem. This database is extremely cheap, is wonderfully robust |
| 727 | and has excellent support. More information is available on the Hughes |
| 728 | Technology \s-1WWW\s0 site at: |
| 729 | .PP |
| 730 | .Vb 1 |
| 731 | \& http://www.hughes.com.au |
| 732 | .Ve |
| 733 | .PP |
| 734 | You may also wish to look at MySQL which is a more powerful database engine |
| 735 | that has a similar feel to mSQL. |
| 736 | .PP |
| 737 | .Vb 1 |
| 738 | \& http://www.tcx.se |
| 739 | .Ve |
| 740 | .PP |
| 741 | If the dataset is larger than 1 million row tables or 1000 tables, or if you |
| 742 | have either more money, or larger machines, I would recommend \fIOracle \s-1RDBMS\s0\fR. |
| 743 | Oracle's \s-1WWW\s0 site is an excellent source of more information. |
| 744 | .PP |
| 745 | .Vb 1 |
| 746 | \& http://www.oracle.com |
| 747 | .Ve |
| 748 | .PP |
| 749 | \&\fIInformix\fR is another high-end \s-1RDBMS\s0 that is worth considering. There are |
| 750 | several differences between Oracle and Informix which are too complex for |
| 751 | this document to detail. Information on Informix can be found on their |
| 752 | \&\s-1WWW\s0 site at: |
| 753 | .PP |
| 754 | .Vb 1 |
| 755 | \& http://www.informix.com |
| 756 | .Ve |
| 757 | .PP |
| 758 | In the case of \s-1WWW\s0 fronted applications, \fImSQL\fR may be a better option |
| 759 | due to slow connection times between a \s-1CGI\s0 script and the Oracle \s-1RDBMS\s0 and |
| 760 | also the amount of resource each Oracle connection will consume. \fImSQL\fR |
| 761 | is lighter resource-wise and faster. |
| 762 | .PP |
| 763 | These views are not necessarily representative of anyone else's opinions, |
| 764 | and do not reflect any corporate sponsorship or views. They are provided |
| 765 | \&\fIas-is\fR. |
| 766 | .Sh "3.8 Is <\fIinsert feature here\fP> supported in \s-1DBI\s0?" |
| 767 | .IX Subsection "3.8 Is <insert feature here> supported in DBI?" |
| 768 | Given that we're making the assumption that the feature you have requested |
| 769 | is a non-standard database-specific feature, then the answer will be \fIno\fR. |
| 770 | .PP |
| 771 | \&\s-1DBI\s0 reflects a \fIgeneric\fR \s-1API\s0 that will work for most databases, and has |
| 772 | no database-specific functionality. |
| 773 | .PP |
| 774 | However, driver authors may, if they so desire, include hooks to database-specific |
| 775 | functionality through the \f(CW\*(C`func()\*(C'\fR method defined in the \s-1DBI\s0 \s-1API\s0. |
| 776 | Script developers should note that use of functionality provided \fIvia\fR |
| 777 | the \f(CW\*(C`func()\*(C'\fR methods is very unlikely to be portable across databases. |
| 778 | .SH "Programming Questions" |
| 779 | .IX Header "Programming Questions" |
| 780 | .Sh "4.1 Is \s-1DBI\s0 any use for \s-1CGI\s0 programming?" |
| 781 | .IX Subsection "4.1 Is DBI any use for CGI programming?" |
| 782 | In a word, yes! \s-1DBI\s0 is hugely useful for \s-1CGI\s0 programming! In fact, I would |
| 783 | tentatively say that \s-1CGI\s0 programming is one of two top uses for \s-1DBI\s0. |
| 784 | .PP |
| 785 | \&\s-1DBI\s0 confers the ability to \s-1CGI\s0 programmers to power WWW-fronted databases |
| 786 | to their users, which provides users with vast quantities of ordered |
| 787 | data to play with. \s-1DBI\s0 also provides the possibility that, if a site is |
| 788 | receiving far too much traffic than their database server can cope with, they |
| 789 | can upgrade the database server behind the scenes with no alterations to |
| 790 | the \s-1CGI\s0 scripts. |
| 791 | .Sh "4.2 How do I get faster connection times with DBD::Oracle and \s-1CGI\s0?" |
| 792 | .IX Subsection "4.2 How do I get faster connection times with DBD::Oracle and CGI?" |
| 793 | .Vb 1 |
| 794 | \& Contributed by John D. Groenveld |
| 795 | .Ve |
| 796 | .PP |
| 797 | The Apache \f(CW\*(C`httpd\*(C'\fR maintains a pool of \f(CW\*(C`httpd\*(C'\fR children to service client |
| 798 | requests. |
| 799 | .PP |
| 800 | Using the Apache \fImod_perl\fR module by \fIDoug MacEachern\fR, the perl |
| 801 | interpreter is embedded with the \f(CW\*(C`httpd\*(C'\fR children. The \s-1CGI\s0, \s-1DBI\s0, and your |
| 802 | other favorite modules can be loaded at the startup of each child. These |
| 803 | modules will not be reloaded unless changed on disk. |
| 804 | .PP |
| 805 | For more information on Apache, see the Apache Project's \s-1WWW\s0 site: |
| 806 | .PP |
| 807 | .Vb 1 |
| 808 | \& http://www.apache.org |
| 809 | .Ve |
| 810 | .PP |
| 811 | The \fImod_perl\fR module can be downloaded from \s-1CPAN\s0 \fIvia\fR: |
| 812 | .PP |
| 813 | .Vb 1 |
| 814 | \& http://www.perl.com/cgi-bin/cpan_mod?module=Apache |
| 815 | .Ve |
| 816 | .Sh "4.3 How do I get persistent connections with \s-1DBI\s0 and \s-1CGI\s0?" |
| 817 | .IX Subsection "4.3 How do I get persistent connections with DBI and CGI?" |
| 818 | .Vb 1 |
| 819 | \& Contributed by John D. Groenveld |
| 820 | .Ve |
| 821 | .PP |
| 822 | Using Edmund Mergl's \fIApache::DBI\fR module, database logins are stored in a |
| 823 | hash with each of these \f(CW\*(C`httpd\*(C'\fR child. If your application is based on a |
| 824 | single database user, this connection can be started with each child. |
| 825 | Currently, database connections cannot be shared between \f(CW\*(C`httpd\*(C'\fR children. |
| 826 | .PP |
| 827 | \&\fIApache::DBI\fR can be downloaded from \s-1CPAN\s0 \fIvia\fR: |
| 828 | .PP |
| 829 | .Vb 1 |
| 830 | \& http://www.perl.com/cgi-bin/cpan_mod?module=Apache::DBI |
| 831 | .Ve |
| 832 | .ie n .Sh "4.4 ``When I run a perl script from the command line, it works, but, when I run it under the ""httpd"", it fails!'' Why?" |
| 833 | .el .Sh "4.4 ``When I run a perl script from the command line, it works, but, when I run it under the \f(CWhttpd\fP, it fails!'' Why?" |
| 834 | .IX Subsection "4.4 ``When I run a perl script from the command line, it works, but, when I run it under the httpd, it fails!'' Why?" |
| 835 | Basically, a good chance this is occurring is due to the fact that the user |
| 836 | that you ran it from the command line as has a correctly configured set of |
| 837 | environment variables, in the case of \fIDBD::Oracle\fR, variables like |
| 838 | \&\f(CW\*(C`ORACLE_HOME\*(C'\fR, \f(CW\*(C`ORACLE_SID\*(C'\fR or \f(CW\*(C`TWO_TASK\*(C'\fR. |
| 839 | .PP |
| 840 | The \f(CW\*(C`httpd\*(C'\fR process usually runs under the user id of \f(CW\*(C`nobody\*(C'\fR, |
| 841 | which implies there is no configured environment. Any scripts attempting to |
| 842 | execute in this situation will correctly fail. |
| 843 | .PP |
| 844 | One way to solve this problem is to set the environment for your database in a |
| 845 | \&\f(CW\*(C`BEGIN { }\*(C'\fR block at the top of your script. Another technique is to configure |
| 846 | your \s-1WWW\s0 server to pass-through certain environment variables to your \s-1CGI\s0 |
| 847 | scripts. |
| 848 | .PP |
| 849 | Similarly, you should check your \f(CW\*(C`httpd\*(C'\fR error logfile for any clues, |
| 850 | as well as the ``Idiot's Guide To Solving Perl / \s-1CGI\s0 Problems'' and |
| 851 | ``Perl \s-1CGI\s0 Programming \s-1FAQ\s0'' for further information. It is |
| 852 | unlikely the problem is DBI\-related. |
| 853 | .PP |
| 854 | The ``Idiot's Guide To Solving Perl / \s-1CGI\s0 Problems'' can be located at: |
| 855 | .PP |
| 856 | .Vb 1 |
| 857 | \& http://www.perl.com/perl/faq/index.html |
| 858 | .Ve |
| 859 | .PP |
| 860 | as can the ``Perl \s-1CGI\s0 Programming \s-1FAQ\s0''. Read \fI\s-1BOTH\s0\fR these documents |
| 861 | carefully! |
| 862 | .ie n .Sh "4.5 How do I get the number of rows returned from a ""SELECT"" statement?" |
| 863 | .el .Sh "4.5 How do I get the number of rows returned from a \f(CWSELECT\fP statement?" |
| 864 | .IX Subsection "4.5 How do I get the number of rows returned from a SELECT statement?" |
| 865 | Count them. Read the \s-1DBI\s0 docs for the \f(CW\*(C`rows()\*(C'\fR method. |
| 866 | .SH "Miscellaneous Questions" |
| 867 | .IX Header "Miscellaneous Questions" |
| 868 | .Sh "5.1 Can I do multi-threading with \s-1DBI\s0?" |
| 869 | .IX Subsection "5.1 Can I do multi-threading with DBI?" |
| 870 | Perl version 5.005 and later can be built to support multi\-threading. |
| 871 | The \s-1DBI\s0, as of version 1.02, does not yet support multi-threading |
| 872 | so it would be unsafe to let more than one thread enter the \s-1DBI\s0 at |
| 873 | the same time. |
| 874 | .PP |
| 875 | It is expected that some future version of the \s-1DBI\s0 will at least be |
| 876 | thread-safe (but not thread\-hot) by automatically blocking threads |
| 877 | intering the \s-1DBI\s0 while it's already in use. |
| 878 | .PP |
| 879 | For some \s-1OCI\s0 example code for Oracle that has multi-threaded \f(CW\*(C`SELECT\*(C'\fR |
| 880 | statements, see: |
| 881 | .PP |
| 882 | .Vb 1 |
| 883 | \& http://www.symbolstone.org/technology/oracle/oci/orathreads.tar.gz |
| 884 | .Ve |
| 885 | .Sh "5.2 How do I handle \s-1BLOB\s0 data with \s-1DBI\s0?" |
| 886 | .IX Subsection "5.2 How do I handle BLOB data with DBI?" |
| 887 | Handling \s-1BLOB\s0 data with the \s-1DBI\s0 is very straight\-forward. \s-1BLOB\s0 columns are |
| 888 | specified in a \s-1SELECT\s0 statement as per normal columns. However, you also |
| 889 | need to specify a maximum \s-1BLOB\s0 size that the <I>database handle</I> can |
| 890 | fetch using the \f(CW\*(C`LongReadLen\*(C'\fR attribute. |
| 891 | .PP |
| 892 | For example: |
| 893 | .PP |
| 894 | .Vb 3 |
| 895 | \& ### $dbh is a connected database handle |
| 896 | \& $sth = $dbh->prepare( "SELECT blob_column FROM blobby_table" ); |
| 897 | \& $sth->execute; |
| 898 | .Ve |
| 899 | .PP |
| 900 | would fail. |
| 901 | .PP |
| 902 | .Vb 3 |
| 903 | \& ### $dbh is a connected database handle |
| 904 | \& ### Set the maximum BLOB size... |
| 905 | \& $dbh->{LongReadLen} = 16384; ### 16Kb...Not much of a BLOB! |
| 906 | .Ve |
| 907 | .PP |
| 908 | .Vb 1 |
| 909 | \& $sth = $dbh->prepare( "..." ); |
| 910 | .Ve |
| 911 | .PP |
| 912 | would succeed <I>provided no column values were larger than the specified |
| 913 | value</I>. |
| 914 | .PP |
| 915 | If the \s-1BLOB\s0 data is longer than the value of \f(CW\*(C`LongReadLen\*(C'\fR, then an |
| 916 | error will occur. However, the \s-1DBI\s0 provides an additional piece of |
| 917 | functionality that will automatically truncate the fetched \s-1BLOB\s0 to the |
| 918 | size of \f(CW\*(C`LongReadLen\*(C'\fR if it is longer. This does not cause an error to |
| 919 | occur, but may make your fetched \s-1BLOB\s0 data useless. |
| 920 | .PP |
| 921 | This behaviour is regulated by the \f(CW\*(C`LongTruncOk\*(C'\fR attribute which is |
| 922 | defaultly set to a false value ( thus making overlong \s-1BLOB\s0 fetches fail ). |
| 923 | .PP |
| 924 | .Vb 3 |
| 925 | \& ### Set BLOB handling such that it's 16Kb and can be truncated |
| 926 | \& $dbh->{LongReadLen} = 16384; |
| 927 | \& $dbh->{LongTruncOk} = 1; |
| 928 | .Ve |
| 929 | .PP |
| 930 | Truncation of \s-1BLOB\s0 data may not be a big deal in cases where the \s-1BLOB\s0 |
| 931 | contains run-length encoded data, but data containing checksums at the end, |
| 932 | for example, a \s-1ZIP\s0 file, would be rendered useless. |
| 933 | .Sh "5.3 How can I invoke stored procedures with \s-1DBI\s0?" |
| 934 | .IX Subsection "5.3 How can I invoke stored procedures with DBI?" |
| 935 | The \s-1DBI\s0 does not define a database-independent way of calling stored procedures. |
| 936 | .PP |
| 937 | However, most database that support them also provide a way to call |
| 938 | them from \s-1SQL\s0 statements \- and the \s-1DBI\s0 certainly supports that. |
| 939 | .PP |
| 940 | So, assuming that you have created a stored procedure within the target |
| 941 | database, \fIeg\fR, an Oracle database, you can use \f(CW$dbh\fR\->\f(CW\*(C`do()\*(C'\fR to |
| 942 | immediately execute the procedure. For example, |
| 943 | .PP |
| 944 | .Vb 1 |
| 945 | \& $dbh->do( "BEGIN someProcedure; END;" ); # Oracle-specific |
| 946 | .Ve |
| 947 | .PP |
| 948 | You should also be able to \f(CW\*(C`prepare\*(C'\fR and \f(CW\*(C`execute\*(C'\fR, which is |
| 949 | the recommended way if you'll be calling the procedure often. |
| 950 | .Sh "5.4 How can I get return values from stored procedures with \s-1DBI\s0?" |
| 951 | .IX Subsection "5.4 How can I get return values from stored procedures with DBI?" |
| 952 | .Vb 1 |
| 953 | \& Contributed by Jeff Urlwin |
| 954 | .Ve |
| 955 | .PP |
| 956 | .Vb 5 |
| 957 | \& $sth = $dbh->prepare( "BEGIN foo(:1, :2, :3); END;" ); |
| 958 | \& $sth->bind_param(1, $a); |
| 959 | \& $sth->bind_param_inout(2, \e$path, 2000); |
| 960 | \& $sth->bind_param_inout(3, \e$success, 2000); |
| 961 | \& $sth->execute; |
| 962 | .Ve |
| 963 | .PP |
| 964 | Remember to perform error checking, though! ( Or use the \f(CW\*(C`RaiseError\*(C'\fR |
| 965 | attribute ). |
| 966 | .Sh "5.5 How can I create or drop a database with \s-1DBI\s0?" |
| 967 | .IX Subsection "5.5 How can I create or drop a database with DBI?" |
| 968 | Database creation and deletion are concepts that are entirely too abstract |
| 969 | to be adequately supported by \s-1DBI\s0. For example, Oracle does not support the |
| 970 | concept of dropping a database at all! Also, in Oracle, the database |
| 971 | \&\fIserver\fR essentially \fIis\fR the database, whereas in mSQL, the |
| 972 | server process runs happily without any databases created in it. The |
| 973 | problem is too disparate to attack in a worthwhile way. |
| 974 | .PP |
| 975 | Some drivers, therefore, support database creation and deletion through |
| 976 | the private \f(CW\*(C`func()\*(C'\fR methods. You should check the documentation for |
| 977 | the drivers you are using to see if they support this mechanism. |
| 978 | .ie n .Sh "5.6 How can I ""commit""\fP or \f(CW""rollback"" a statement with \s-1DBI\s0?" |
| 979 | .el .Sh "5.6 How can I \f(CWcommit\fP or \f(CWrollback\fP a statement with \s-1DBI\s0?" |
| 980 | .IX Subsection "5.6 How can I commit or rollback a statement with DBI?" |
| 981 | See the \f(CW\*(C`commit()\*(C'\fR and \f(CW\*(C`rollback()\*(C'\fR methods in the \s-1DBI\s0 Specification. |
| 982 | .PP |
| 983 | Chapter 6 of \*(L"Programming the Perl \s-1DBI\s0\*(R" discusses transaction handling within |
| 984 | the context of \s-1DBI\s0 in more detail. |
| 985 | .ie n .Sh "5.7 How are ""NULL"" values handled by \s-1DBI\s0?" |
| 986 | .el .Sh "5.7 How are \f(CWNULL\fP values handled by \s-1DBI\s0?" |
| 987 | .IX Subsection "5.7 How are NULL values handled by DBI?" |
| 988 | \&\f(CW\*(C`NULL\*(C'\fR values in \s-1DBI\s0 are specified to be treated as the value \f(CW\*(C`undef\*(C'\fR. |
| 989 | \&\f(CW\*(C`NULL\*(C'\fRs can be inserted into databases as \f(CW\*(C`NULL\*(C'\fR, for example: |
| 990 | .PP |
| 991 | .Vb 1 |
| 992 | \& $rv = $dbh->do( "INSERT INTO table VALUES( NULL )" ); |
| 993 | .Ve |
| 994 | .PP |
| 995 | but when queried back, the \f(CW\*(C`NULL\*(C'\fRs should be tested against \f(CW\*(C`undef\*(C'\fR. |
| 996 | This is standard across all drivers. |
| 997 | .ie n .Sh "5.8 What are these ""func()"" methods all about?" |
| 998 | .el .Sh "5.8 What are these \f(CWfunc()\fP methods all about?" |
| 999 | .IX Subsection "5.8 What are these func() methods all about?" |
| 1000 | The \f(CW\*(C`func()\*(C'\fR method is defined within \s-1DBI\s0 as being an entry point |
| 1001 | for database-specific functionality, \fIeg\fR, the ability to create or |
| 1002 | drop databases. Invoking these driver-specific methods is simple, for example, |
| 1003 | to invoke a \f(CW\*(C`createDatabase\*(C'\fR method that has one argument, we would |
| 1004 | write: |
| 1005 | .PP |
| 1006 | .Vb 1 |
| 1007 | \& $rv =$dbh->func( 'argument', 'createDatabase' ); |
| 1008 | .Ve |
| 1009 | .PP |
| 1010 | Software developers should note that the \f(CW\*(C`func()\*(C'\fR methods are |
| 1011 | non-portable between databases. |
| 1012 | .Sh "5.9 Is \s-1DBI\s0 Year 2000 Compliant?" |
| 1013 | .IX Subsection "5.9 Is DBI Year 2000 Compliant?" |
| 1014 | \&\s-1DBI\s0 has no knowledge of understanding of what dates are. Therefore, \s-1DBI\s0 |
| 1015 | itself does not have a Year 2000 problem. Individual drivers may use date |
| 1016 | handling code internally and therefore be potentially susceptible to the |
| 1017 | Year 2000 problem, but this is unlikely. |
| 1018 | .PP |
| 1019 | You may also wish to read the ``Does Perl have a Year 2000 problem?'' section |
| 1020 | of the Perl \s-1FAQ\s0 at: |
| 1021 | .PP |
| 1022 | .Vb 1 |
| 1023 | \& http://www.perl.com/CPAN/doc/FAQs/FAQ/PerlFAQ.html |
| 1024 | .Ve |
| 1025 | .SH "Support and Training" |
| 1026 | .IX Header "Support and Training" |
| 1027 | The Perl5 Database Interface is \fI\s-1FREE\s0\fR software. \s-1IT\s0 \s-1COMES\s0 \s-1WITHOUT\s0 \s-1WARRANTY\s0 |
| 1028 | \&\s-1OF\s0 \s-1ANY\s0 \s-1KIND\s0. See the \s-1DBI\s0 \s-1README\s0 for more details. |
| 1029 | .PP |
| 1030 | However, some organizations are providing either technical support or |
| 1031 | training programs on \s-1DBI\s0. The present author has no knowledge as |
| 1032 | to the quality of these services. The links are included for reference |
| 1033 | purposes only and should not be regarded as recommendations in any way. |
| 1034 | \&\fICaveat emptor\fR. |
| 1035 | .Sh "Commercial Support" |
| 1036 | .IX Subsection "Commercial Support" |
| 1037 | .IP "The Perl Clinic" 4 |
| 1038 | .IX Item "The Perl Clinic" |
| 1039 | The Perl Clinic provides commercial support for \fIPerl\fR and Perl |
| 1040 | related problems, including the \fI\s-1DBI\s0\fR and its drivers. Support is |
| 1041 | provided by the company with whom Tim Bunce, author of \fI\s-1DBI\s0\fR and |
| 1042 | \&\fIDBD::Oracle\fR, works and ActiveState. For more information on their |
| 1043 | services, please see: |
| 1044 | .Sp |
| 1045 | .Vb 1 |
| 1046 | \& http://www.perlclinic.com |
| 1047 | .Ve |
| 1048 | .Sh "Training" |
| 1049 | .IX Subsection "Training" |
| 1050 | .IP "Westlake Solutions" 4 |
| 1051 | .IX Item "Westlake Solutions" |
| 1052 | A hands-on class for experienced Perl \s-1CGI\s0 developers that teaches |
| 1053 | how to write database-connected \s-1CGI\s0 scripts using Perl and \s-1DBI\s0.pm. This |
| 1054 | course, along with four other courses on \s-1CGI\s0 scripting with Perl, is |
| 1055 | taught in Washington, \s-1DC\s0; Arlington, Virginia; and on-site worldwide upon |
| 1056 | request. |
| 1057 | .Sp |
| 1058 | See: |
| 1059 | .Sp |
| 1060 | .Vb 1 |
| 1061 | \& http://www.westlake.com/training |
| 1062 | .Ve |
| 1063 | .Sp |
| 1064 | for more details. |
| 1065 | .SH "Other References" |
| 1066 | .IX Header "Other References" |
| 1067 | In this section, we present some miscellaneous \s-1WWW\s0 links that may be of |
| 1068 | some interest to \s-1DBI\s0 users. These are not verified and may result in |
| 1069 | unknown sites or missing documents. |
| 1070 | .PP |
| 1071 | .Vb 3 |
| 1072 | \& http://www-ccs.cs.umass.edu/db.html |
| 1073 | \& http://www.odmg.org/odmg93/updates_dbarry.html |
| 1074 | \& http://www.jcc.com/sql_stnd.html |
| 1075 | .Ve |
| 1076 | .SH "AUTHOR" |
| 1077 | .IX Header "AUTHOR" |
| 1078 | Alligator Descartes <\fIhttp://www.symbolstone.org/descarte/contact.html\fR>. |
| 1079 | Portions are Copyright their original stated authors. |
| 1080 | .SH "COPYRIGHT" |
| 1081 | .IX Header "COPYRIGHT" |
| 1082 | This document is Copyright (c)1994\-2000 Alligator Descartes, with portions |
| 1083 | Copyright (c)1994\-2000 their original authors. This module is released under |
| 1084 | the 'Artistic' license which you can find in the perl distribution. |
| 1085 | .PP |
| 1086 | This document is Copyright (c)1997\-2000 Alligator Descartes. All rights reserved. |
| 1087 | Permission to distribute this document, in full or in part, via email, |
| 1088 | Usenet, ftp archives or http is granted providing that no charges are involved, |
| 1089 | reasonable attempt is made to use the most current version and all credits |
| 1090 | and copyright notices are retained ( the \fI\s-1AUTHOR\s0\fR and \fI\s-1COPYRIGHT\s0\fR sections ). |
| 1091 | Requests for other distribution rights, including incorporation into |
| 1092 | commercial products, such as books, magazine articles or CD-ROMs should be |
| 1093 | made to Alligator Descartes <\fIhttp://www.symbolstone.org/descarte/contact.html\fR>. |