1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/sql-driver.doc:35 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>SQL Module - Drivers</title>
<style type="text/css"><!--
fn { margin-left: 1cm; text-indent: -1cm; }
a:link { color: #004faf; text-decoration: none }
a:visited { color: #672967; text-decoration: none }
body { background: #ffffff; color: black; }
--></style>
</head>
<body>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr bgcolor="#E5E5E5">
<td valign=center>
<a href="index.html">
<font color="#004faf">Home</font></a>
| <a href="classes.html">
<font color="#004faf">All Classes</font></a>
| <a href="mainclasses.html">
<font color="#004faf">Main Classes</font></a>
| <a href="annotated.html">
<font color="#004faf">Annotated</font></a>
| <a href="groups.html">
<font color="#004faf">Grouped Classes</font></a>
| <a href="functions.html">
<font color="#004faf">Functions</font></a>
</td>
<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>SQL Module - Drivers</h1>
<p> <ul>
<li> <a href="#Introduction">Introduction</a>
<li> <a href="#building">Building the drivers using configure</a>
<li> <a href="#buildingmanually">Building the plugins manually</a>
<ul>
<li> <a href="#TQDB2">TQDB2</a> - IBM DB2 Driver (v7.1 and higher)
<li> <a href="#TQIBASE">TQIBASE</a> - Borland Interbase Driver
<li> <a href="#TQMYSQL3">TQMYSQL3</a> - MySQL Driver
<li> <a href="#TQOCI8">TQOCI8</a> - Oracle Call Interface Driver, version 8 and 9
<li> <a href="#TQODBC3">TQODBC3</a> - Open Database Connectivity Driver
<li> <a href="#TQPSQL7">TQPSQL7</a> - PostgreSQL v6.x and v7.x Driver
<li> <a href="#TQSQLITE">TQSQLITE</a> - SQLite Driver
<li> <a href="#TQTDS7">TQTDS7</a> - Sybase Adaptive Server
</ul>
<li> <a href="#troubleshooting">Troubleshooting</a>
<li> <a href="#development">How to write your own database driver</a>
</ul>
<p> <a name="Introduction"></a>
<h2> Introduction
</h2>
<a name="1"></a><p> The <a href="sql.html">SQL Module</a> uses driver <a href="plugins-howto.html">plugins</a> in order to communicate with
different database APIs. Since the SQL Module API is
database-independent, all database-specific code is contained within
these drivers. Several drivers are supplied with TQt and other drivers
can be added. The driver source code is supplied and can be used as a
model for <a href="#development">writing your own drivers</a>.
<p> <em>Note:</em> To build a driver plugin you need to have the appropriate
client library for your Database Management System (DBMS). This provides
access to the API exposed by the DBMS, and is typically shipped with it.
Most installation programs also allow you to install "development
libraries", and these are what you need. These libraries are responsible
for the low-level communication with the DBMS.
<p> The drivers shipped with TQt are:
<ul>
<li> <a href="#TQDB2">TQDB2</a> - IBM DB2 Driver (v7.1 and higher)
<li> <a href="#TQIBASE">TQIBASE</a> - Borland Interbase Driver
<li> <a href="#TQMYSQL3">TQMYSQL3</a> - MySQL Driver
<li> <a href="#TQOCI8">TQOCI8</a> - Oracle Call Interface Driver, version 8, 9 and 10
<li> <a href="#TQODBC3">TQODBC3</a> - Open Database Connectivity Driver
<li> <a href="#TQPSQL7">TQPSQL7</a> - PostgreSQL v6.x and v7.x Driver
<li> <a href="#TQSQLITE">TQSQLITE</a> - SQLite Driver
<li> <a href="#TQTDS7">TQTDS7</a> - Sybase Adaptive Server
</ul>
<p> Note that not all of the plugins are shipped with the TQt Open Source Edition
due to license incompatibilities with the GPL.
<p> <a name="building"></a>
<h2> Building the drivers using configure
</h2>
<a name="2"></a><p> The TQt configure script automatically detects the available client
libraries on your machine. Run "configure -help" to see what drivers
can be built. You should get an output similar to this:
<p> <pre>
Possible values for <driver>: [ mysql oci odbc psql tds ]
Auto-Detected on this system: [ mysql psql ]
</pre>
<p> Note that on Windows, the configure script doesn't do any
auto-detection.
<p> The configure script cannot detect the neccessary libraries and include
files if they are not in the standard paths, so it may be necessary to
specify these paths using the "-I" and "-L" switches. For example, if
your MySQL include files are installed in <tt>/usr/local/mysql</tt> (or in
<tt>C:\mysql\include</tt>
configure: <tt>-I/usr/local/mysql</tt> (or <tt>-I C:\mysql\include</tt>
Windows).
<p> On Windows the -I parameter doesn't accept spaces in
filenames, so use the 8.3 name instead, i.e. use <tt>C:\progra~1\mysql</tt>
instead of <tt>C:\program files\mysql</tt>.
<p> Use the <tt>-qt-sql-<driver></tt> parameter to build the database driver
statically into your TQt library or <tt>-plugin-sql-<driver></tt> to build
the driver as a plugin. Look at the sections that follow for
additional information about required libraries.
<p> <a name="buildingmanually"></a>
<h2> Building the plugins manually
</h2>
<a name="3"></a><p> <a name="TQMYSQL3"></a>
<h3> TQMYSQL3 - MySQL 3.x and MySQL 4.x
</h3>
<a name="3-1"></a><p> <!-- index TQMYSQL3 --><a name="TQMYSQL3"></a>
<p> <h4> General information
</h4>
<a name="3-1-1"></a><p> MySQL 3.x doesn't support SQL transactions by default. There are some
backends which offer this functionality. Recent versions of the MySQL
client libraries (>3.23.34) allow you to use transactions on those
modified servers.
<p> If you have a recent client library and connect to a
transaction-enabled MySQL server, a call to the
<a href="ntqsqldriver.html#hasFeature">TQSqlDriver::hasFeature</a>( TQSqlDriver::Transactions ) function returns
TRUE and SQL transactions can be used.
<p> If the plugin is compiled against MySQL 4.x client libraries,
transactions are enabled by default.
<p> You can find information about MySQL on <a href="http://www.mysql.com">http://www.mysql.com</a>
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-1-2"></a><p> You need the MySQL header files and as well as the shared library
<tt>libmysqlclient.so</tt>. Depending on your Linux distribution you need to
install a package which is usually called "mysql-devel".
<p> Tell <a href="qmake-manual.html">qmake</a> where to find the MySQL
header files and shared libraries (here it is assumed that MySQL is
installed in <tt>/usr/local</tt>) and run <tt>make</tt>:
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/mysql
qmake -o Makefile "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient" mysql.pro
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-1-3"></a><p> You need to get the MySQL installation files. Run SETUP.EXE and
choose "Custom Install". Install the "Libs & Include Files" Module.
Build the plugin as follows (here it is assumed that MySQL is
installed in <tt>C:\MYSQL</tt>):
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\mysql
qmake -o Makefile "INCLUDEPATH+=C:\MYSQL\INCLUDE" "LIBS+=C:\MYSQL\LIB\OPT\LIBMYSQL.LIB" mysql.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace <tt>nmake</tt> with <tt>make</tt> in the statement above.
<p> <a name="TQOCI8"></a>
<h3> TQOCI8 - Oracle Call Interface (OCI)
</h3>
<a name="3-2"></a><p> <!-- index TQOCI8 --><a name="TQOCI8"></a>
<p> <h4> General information
</h4>
<a name="3-2-1"></a><p> The TQt OCI plugin supports both Oracle 8 and Oracle 9. After
connecting to the Oracle server, the plugin will auto-detect the
database version and enable features accordingly.
<p> <h4> Unicode support
</h4>
<a name="3-2-2"></a><p> If the Oracle server supports Unicode, the OCI plugin will use UTF-8
encoding to communicate with the server.
<p> <h4> BLOB/LOB support
</h4>
<a name="3-2-3"></a><p> Binary Large Objects (BLOBs) can be read and written, but be aware
that this process may require a lot of memory.
<p> Note that Oracle 9 doesn't support scrollable result sets with LOB
columns, you have to use a forward only query to select LOB fields
(see <a href="ntqsqlquery.html#setForwardOnly">TQSqlQuery::setForwardOnly</a>()).
<p> Inserting BLOBs should be done using either a prepared query where the
BLOBs are bound to placeholders, or <a href="ntqsqlcursor.html">TQSqlCursor</a> which uses a prepared
query to do this internally (see $TQTDIR/examples/sql/blob).
<p> <h4> Know problems
</h4>
<a name="3-2-4"></a><p> When a query is in forward only mode a call to <a href="ntqsqlquery.html#last">TQSqlQuery::last</a>() will
position the query on the last record and return TRUE, but subsequent
calls to <a href="ntqsqlquery.html#value">TQSqlQuery::value</a>() will only return NULLs.
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-2-5"></a><p> All files required to build driver should ship with the standard Oracle
Client install.
<p> Oracle library files required to build driver:
<p> <ul>
<li> <tt>libclntsh.so</tt> (all versions)
<li> <tt>libwtc8.so</tt> (only Oracle 8) or <tt>libwtc9.so</tt> (only Oracle 9)
</ul>
<p> Tell <tt>qmake</tt> where to find the Oracle header files and shared
libraries (it is assumed that the variable <tt>$ORACLE_HOME</tt> points to
the directory where Oracle is installed) and run make:
<p> If you are using Oracle 8:
<pre>
cd $TQTDIR/plugins/src/sqldrivers/oci
qmake -o Makefile "INCLUDEPATH+=$ORACLE_HOME/rdbms/public $ORACLE_HOME/rdbms/demo" "LIBS+=-L$ORACLE_HOME/lib -lclntsh -lwtc8" oci.pro
make
</pre>
<p> For Oracle version 9:
<pre>
cd $TQTDIR/plugins/src/sqldrivers/oci
qmake -o Makefile "INCLUDEPATH+=$ORACLE_HOME/rdbms/public $ORACLE_HOME/rdbms/demo" "LIBS+=-L$ORACLE_HOME/lib -lclntsh -lwtc9" oci.pro
make
</pre>
<p> For Oracle version 10:
<pre>
cd $TQTDIR/plugins/src/sqldrivers/oci
qmake -o Makefile "INCLUDEPATH+=$ORACLE_HOME/rdbms/public $ORACLE_HOME/rdbms/demo" "LIBS+=-L$ORACLE_HOME/lib -lclntsh" oci.pro
make
</pre>
<p> Note that some versions of the OCI client libraries contain a bug
that makes programs linked to these libraries segfault on exit. This
only happens if the TQOCI8 driver is compiled as a plugin. To work
around this problem, either compile the driver into the TQt libray
itself, or configure TQt with the option '-DTQT_NO_LIBRARY_UNLOAD'.
For Oracle 9, it is possible to link to the static OCI library by
using "LIBS+=$ORACLE_HOME/lib/libclntst9.a".
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-2-6"></a><p> Choosing the option "Programmer" in the Oracle Client Installer from
the Oracle Client Installation CD is sufficient to build the plugin.
<p> Build the plugin as follows (here it is assumed that Oracle Client is
installed in <tt>C:\oracle</tt>):
<p> <pre>
set INCLUDE=%INCLUDE%;c:\oracle\oci\include
set LIB=%LIB%;c:\oracle\oci\lib\msvc
cd %TQTDIR%\plugins\src\sqldrivers\oci
qmake -o Makefile oci.pro
nmake
</pre>
<p> When you run your application you will also need to add the <tt>oci.dll</tt>
path to your <tt>PATH</tt> environment variable:
<p> <pre>
set PATH=%PATH%;c:\oracle\bin
</pre>
<p> If you are not using a Microsoft compiler, replace <tt>nmake</tt> with <tt>make</tt> in the statement above.
<p> <a name="TQODBC3"></a>
<h3> TQODBC3 - Open Database Connectivity (ODBC)
</h3>
<a name="3-3"></a><p> <!-- index TQODBC3 --><a name="TQODBC3"></a>
<p> <h4> General information
</h4>
<a name="3-3-1"></a><p> ODBC is a general interface that allows you to connect to multiple
DBMS using a common interface. The TQODBC3 driver allows you to connect
to an ODBC driver manager and access the available data sources. Note
that you also need to install and configure ODBC drivers for the ODBC
driver manager that is installed on your system. The TQODBC3 plugin
then allows you to use these data sources in your TQt project.
<p> On Windows systems after 95 an ODBC driver manager should be installed
by default, for Unix systems there are some implementations which must
be installed first. Note that every client that uses your application
is required to have an ODBC driver manager installed, otherwise the
TQODBC3 plugin will not work.
<p> Be aware that when connecting to an ODBC datasource you must pass in
the name of the ODBC datasource to the <a href="ntqsqldatabase.html#setDatabaseName">TQSqlDatabase::setDatabaseName</a>()
function: not the actual database name.
<p> The TQODBC3 Plugin needs an ODBC compliant driver manager version 2.0 or
later to work. Some ODBC drivers claim to be version 2.0 compliant,
but do not offer all the necessary functionality. The TQODBC3 plugin
therefore checks whether the data source can be used after a
connection has been established and refuses to work if the check
fails. If you don't like this behaviour, you can remove the <tt>#define ODBC_CHECK_DRIVER</tt> line from the file <tt>qsql_odbc.cpp</tt>. Do this at
your own risk!
<p> If you experience very slow access of the ODBC datasource, make sure
that ODBC call tracing is turned off in the ODBC datasource manager.
<p> <h4> Unicode support
</h4>
<a name="3-3-2"></a><p> The TQODBC3 Plugin will use the Unicode API if UNICODE is defined. On
Windows NT based systems, this is the default. Note that the ODBC
driver and the DBMS have to support Unicode as well.
<p> For the Oracle 9 ODBC driver (Windows), it is neccessary to check
"SQL_WCHAR support" in the ODBC driver manager otherwise Oracle
will convert all Unicode strings to local 8 bit.
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-3-3"></a><p> It is recommended that you use unixODBC. You can find the latest
version and ODBC drivers at <a href="http://www.unixodbc.org">http://www.unixodbc.org</a>.
You need the unixODBC header files and shared libraries.
<p> Tell <tt>qmake</tt> where to find the unixODBC header files and shared
libraries (here it is assumed that unixODBC is installed in
<tt>/usr/local/unixODBC</tt>) and run <tt>make</tt>:
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/odbc
qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc"
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-3-4"></a><p> The ODBC header and include files should already be installed in the
right directories. You just have to build the plugin as follows:
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\odbc
qmake -o Makefile odbc.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace <tt>nmake</tt> with <tt>make</tt> in the statement above.
<p> <a name="TQPSQL7"></a>
<h3> TQPSQL7 - PostgreSQL version 6 and 7
</h3>
<a name="3-4"></a><p> <!-- index TQPSQL7 --><a name="TQPSQL7"></a>
<p> <h4> General information
</h4>
<a name="3-4-1"></a><p> The TQPSQL7 driver supports both version 6 and 7 of PostgreSQL. We
recommend compiling the plugin with a recent version of the PostgreSQL
client library (libpq) because it is more stable and still backwards
compatible.
<p> If you want to link the plugin against the libpq shipped with version
6 we recommend a recent version like PostgreSQL 6.5.3, otherwise a
connection to a version 7 server may not work.
<p> The driver auto-detects the server version of PostgreSQL after a
connection was successful. If the server is too old or the version
information cannot be determined a warning is issued.
<p> For more information about PostgreSQL visit <a href="http://www.postgresql.org">http://www.postgresql.org</a>.
<p> <h4> Unicode support
</h4>
<a name="3-4-2"></a><p> The TQPSQL7 driver automatically detects whether the PostgreSQL
database you are connecting to supports Unicode or not. Unicode is
automatically used if the server supports it. Note that the driver
only supports the UTF-8 encoding. If your database uses any other
encoding, the server must be compiled with Unicode conversion
support.
<p> Unicode support was introduced in PostgreSQL version 7.1 and it will
only work if both the server and the client library have been compiled
with multibyte support. More information about how to set up a
multibyte enabled PostgreSQL server can be found in the PostgreSQL
Administrator Guide, Chapter 5.
<p> <h4> BLOB support
</h4>
<a name="3-4-3"></a><p> Binary Large Objects are supported through the <tt>BYTEA</tt> field type in
PostgreSQL versions >= 7.1. Fields of type <tt>OID</tt> can be read, but not
written. Use the PostgreSQL command <tt>lo_import</tt> to insert binary data
into <tt>OID</tt> fields.
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-4-4"></a><p> Just installing the pq client library and the corresponding header
files is not sufficient. You have to get the PostgreSQL source
distribution and run the configure script. If you've already installed
a binary distribution you don't need to build it. The source
distribution is needed because the TQPSQL7 plugin relies on a couple of
header files that are usually not a part of the binary distribution.
<p> To make <tt>qmake</tt> find the PostgreSQL header files and shared
libraries, run <tt>qmake</tt> the following way (assuming that the
PostgreSQL sources can be found in <tt>/usr/src/psql</tt>):
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/psql
qmake -o Makefile "INCLUDEPATH+=/usr/src/psql/src/include /usr/src/psql/src/interfaces/libpq" "LIBS+=-L/usr/lib -lpq" psql.pro
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-4-5"></a><p> Unpack and build the PostgreSQL source distribution as described in
the PostgreSQL documentation. Assuming the PostgreSQL sources resides
in <tt>C:\psql</tt>, build the plugin as follows:
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\psql
qmake -o Makefile "INCLUDEPATH+=C:\psql\src\include C:\psql\src\interfaces\libpq" psql.pro
nmake
</pre>
<p> Remember to add the path to the <tt>libpq.dll</tt> library to your PATH
environment variable so that Windows can find it. In this case that
would be <tt>C:\psql\src\interfaces\libpq\Release</tt>. If you are not using a
Microsoft compiler, replace <tt>nmake</tt> with <tt>make</tt> in the statement
above.
<p> <a name="TQTDS7"></a>
<h3> TQTDS7 - Sybase Adaptive Server
</h3>
<a name="3-5"></a><p> <!-- index TQTDS7 --><a name="TQTDS7"></a>
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-5-1"></a><p> Under Unix, two libraries are available which support the TDS protocol:
<p> - FreeTDS, a free implementation of the TDS protocol
(<a href="http://www.freetds.org">http://www.freetds.org</a>). Note that FreeTDS is not yet stable,
so some functionality may not work as expected.
<p> - Sybase Open Client, available from <a href="http://www.sybase.com">http://www.sybase.com</a>.
Note for Linux users: Get the Open Client RPM from
<a href="http://linux.sybase.com">http://linux.sybase.com</a>.
<p> Regardless of which library you use, the shared object file
<tt>libsybdb.so</tt> is needed. Set the SYBASE environment variable to
point to the directory where you installed the client library and
execute <tt>qmake</tt>:
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/tds
qmake -o Makefile "INCLUDEPATH=$SYBASE/include" "LIBS=-L$SYBASE/lib -lsybdb"
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-5-2"></a><p> You can either use the DB-Library supplied by Microsoft or the Sybase
Open Client (<a href="http://www.sybase.com">http://www.sybase.com</a>). You must include <tt>NTWDBLIB.LIB</tt> to build the plugin:
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\tds
qmake -o Makefile "LIBS+=NTWDBLIB.LIB" tds.pro
nmake
</pre>
<p> By default the Microsoft library is used on Windows, if you want to force
the use of the Sybase Open Client, you must define
<tt>Q_USE_SYBASE</tt> in <tt>%TQTDIR%\src\sql\drivers\tds\qsql_tds.cpp</tt>.
<p> <a name="TQDB2"></a>
<h3> TQDB2 - IBM DB2 Driver (v7.1 or higher)
</h3>
<a name="3-6"></a><p> <!-- index TQDB2 --><a name="TQDB2"></a>
<p> <h4> General information
</h4>
<a name="3-6-1"></a><p> The TQt DB2 plugin makes it possible to access IBM DB2 databases. It
has been tested with IBM DB2 v7.1 and 7.2. You have to install the IBM
DB2 development client library, which contains the header and library
files necessary for compiling the TQDB2 plugin.
<p> The TQDB2 driver supports prepared queries, reading/writing of Unicode
strings and reading/writing of BLOBs.
<p> We suggest using a forward-only query when calling stored procedures
in DB2 (see <a href="ntqsqlquery.html#setForwardOnly">TQSqlQuery::setForwardOnly</a>()).
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-6-2"></a><p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/db2
qmake -o Makefile "INCLUDEPATH+=$DB2DIR/include" "LIBS+=-L$DB2DIR/lib -ldb2"
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-6-3"></a><p> The DB2 header and include files should already be installed in the
right directories. You just have to build the plugin as follows:
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\db2
qmake -o Makefile "INCLUDEPATH+=<DB2 home>/sqllib/include" "LIBS+=<DB2 home>/sqllib/lib/db2cli.lib"
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace <tt>nmake</tt>
with <tt>make</tt> in the statement above.
<p> <a name="TQSQLITE"></a>
<h3> TQSQLITE - SQLite Driver
</h3>
<a name="3-7"></a><p> <!-- index TQSQLITE --><a name="TQSQLITE"></a>
<p> The TQt SQLite plugin makes it possible to access SQLite databases.
SQLite is an in-process database, meaning that it is not necessary
to have a database server. SQLite operates on a single file, which has
to be set as database name when opening a connection. If the file does
not exist, SQLite will try to create it. SQLite also supports in-memory
databases, simply pass ":memory:" as the database name.
<p> SQLite has some restrictions regarding multiple users and
multiple transactions. If you try to read/write on a resource from different
transactions, your application might freeze until one transaction commits
or rolls back.
<p> SQLite has no support for types, every value is treated as character data.
BLOBs are therefore not supported.
<p> You can find information about SQLite on <a href="http://www.sqlite.org">http://www.sqlite.org</a>.
<p> SQLite is shipped as third party library within TQt. It can be built by
passing the following parameters to the configure script:
<tt>-plugin-sql-sqlite</tt> (as plugin) or <tt>-qt-sql-sqlite</tt> (linked
directly into the TQt library).
<p> If you don't want to use the SQLite library shipped with TQt, you can
build it manually (replace <tt>$SQLITE</tt> by the directory where SQLite
resides):
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/sqlite
qmake -o Makefile "INCLUDEPATH+=$SQLITE/include" "LIBS+=-L$SQLITE/lib -lsqlite"
make
</pre>
<p> <a name="TQIBASE"></a>
<h3> TQIBASE - Borland Interbase Driver
</h3>
<a name="3-8"></a><p> <!-- index TQIBASE --><a name="TQIBASE"></a>
<p> <h4> General information
</h4>
<a name="3-8-1"></a><p> The TQt Interbase plugin makes it possible to access the Interbase and
Firebird databases. Interbase can either be used as a client/server or
without a server operating on local files. The database file must
exist before a connection can be established.
<p> Note that Interbase requires you to specify the full path to the
database file, no matter whether it is stored locally or on another
server.
<p> <pre>
myDatabase->setHostName("MyServer");
myDatabase->setDatabaseName("C:\\test.gdb");
</pre>
<p> You need the Interbase/Firebird development headers and libraries
to build this plugin.
<p> Due to the GPL, users of the TQt Open Source Edition are not allowed to link
this plugin to the commercial editions of Interbase. Please use Firebird
or the free edition of Interbase.
<p> <h4> How to build the plugin on Unix/Linux
</h4>
<a name="3-8-2"></a><p> The following assumes Interbase or Firebird is installed in
<tt>/opt/interbase</tt>:
<p> <pre>
cd $TQTDIR/plugins/src/sqldrivers/ibase
qmake -o Makefile "INCLUDEPATH+=/opt/interbase/include" "LIBS+=-L/opt/interbase/lib" ibase.pro
make
</pre>
<p> <h4> How to build the plugin on Windows
</h4>
<a name="3-8-3"></a><p> The following assumes Interbase or Firebird is installed in
<tt>C:\interbase</tt>:
<p> <pre>
cd %TQTDIR%\plugins\src\sqldrivers\ibase
qmake -o Makefile "INCLUDEPATH+=C:\interbase\include" ibase.pro
nmake
</pre>
<p> If you are not using a Microsoft compiler, replace <tt>nmake</tt>
with <tt>make</tt> in the statement above.
<p> Note that <tt>C:\interbase\bin</tt> must be in the PATH.
<p> <a name="troubleshooting"></a>
<h2> Troubleshooting
</h2>
<a name="4"></a><p> You should always use client libraries that have been compiled with
the same compiler as you are using for your project. If you cannot get
a source distibution to compile the client libraries yourself, you
must make sure that the pre-compiled library is compatible with
your compiler, otherwise you will get a lot of "undefined symbols"
errors. Some compilers have tools to convert libraries, e.g. Borland
ships the tool <tt>COFF2OMF.EXE</tt> to convert libraries that have been
generated with Microsoft Visual C++.
<p> If the compilation of a plugin succeeds but it cannot be loaded,
make sure that the following requirements are met:
<p> <ul>
<li> Ensure that you are using a shared TQt library; you cannot use the
plugins with a static build.
<li> Ensure that the environment variable <tt>TQTDIR</tt> points to the right
directory. Go to the <tt>$TQTDIR/plugins/sqldrivers</tt> directory and
make sure that the plugin exists in that directory.
<li> Ensure that the client libraries of the DBMS are available on the
system. On Unix, run the command <tt>ldd</tt> and pass the name of the
plugin as parameter, for example <tt>ldd libqsqlmysql.so</tt>. You will
get a warning if any of the client libraries couldn't be found.
On Windows, you can use the dependency walker of Visual Studio.
</ul>
<p> If you are experiencing problems with loading plugins, and see output
like this
<p> <pre>
TQSqlDatabase warning: TQMYSQL3 driver not loaded
TQSqlDatabase: available drivers: TQMYSQL3
</pre>
<p> the problem is probably that the plugin had the wrong build key. For
debugging purposes, remove the corresponding entry in the
$HOME/.qt/qt_plugins_(qtversion).rc file.
<p> The next time you try to load this plugin, it will give you a more detailed
error message.
<p> <a name="development"></a>
<h2> How to write your own database driver
</h2>
<a name="5"></a><p> <a href="ntqsqldatabase.html">TQSqlDatabase</a> is responsible for loading and managing database driver
plugins. When a database is added (see <a href="ntqsqldatabase.html#addDatabase">TQSqlDatabase::addDatabase</a>()),
the appropriate driver plugin is loaded (using <a href="ntqsqldriverplugin.html">TQSqlDriverPlugin</a>).
TQSqlDatabase relies on the driver plugin to provide interfaces for
<a href="ntqsqldriver.html">TQSqlDriver</a> and <a href="ntqsqlresult.html">TQSqlResult</a>.
<p> TQSqlDriver is an abstract base class which defines the functionality
of a SQL database driver. This includes functions such as
<a href="ntqsqldriver.html#open">TQSqlDriver::open</a>() and <a href="ntqsqldriver.html#close">TQSqlDriver::close</a>(). TQSqlDriver is responsible
for connecting to a database, establish the proper environment, etc.
In addition, TQSqlDriver can create <a href="ntqsqlquery.html">TQSqlQuery</a> objects appropriate for
the particular database API. TQSqlDatabase forwards many of its
function calls directly to TQSqlDriver which provides the concrete
implementation.
<p> TQSqlResult is an abstract base class which defines the functionality
of a SQL database query. This includes statements such as <tt>SELECT</tt>,
<tt>UPDATE</tt>, and <tt>ALTER TABLE</tt>. TQSqlResult contains functions such as
TQSqlResult::next() and TQSqlResult::value(). TQSqlResult is responsible
for sending queries to the database, returning result data, etc.
TQSqlQuery forwards many of its function calls directly to <a href="ntqsqlresult.html">TQSqlResult</a>
which provides the concrete implementation.
<p> <a href="ntqsqldriver.html">TQSqlDriver</a> and TQSqlResult are closely connected. When implementing a
TQt SQL driver, both of these classes must to be subclassed and the
abstract virtual methods in each class must be implemented.
<p> To implement a TQt SQL driver as a plugin (so that it is recognized and
loaded by the TQt library at runtime), the driver must use the
<tt>Q_EXPORT_PLUGIN</tt> macro. Read the <a href="plugins-howto.html">TQt
Plugin</a> documentation for more information on this. You can
also check out how this is done in the SQL plugins that is provided
with TQt in <tt>TQTDIR/plugins/src/sqldrivers</tt> and
<tt>TQTDIR/src/sql/drivers</tt>.
<p> The following code can be used as a skeleton for a SQL driver:
<p> <pre>
class TQNullResult : public <a href="ntqsqlresult.html">TQSqlResult</a>
{
public:
TQNullResult( const <a href="ntqsqldriver.html">TQSqlDriver</a>* d ): <a href="ntqsqlresult.html">TQSqlResult</a>( d ) {}
~TQNullResult() {}
protected:
<a href="ntqvariant.html">TQVariant</a> data( int ) { return TQVariant(); }
bool reset ( const <a href="ntqstring.html">TQString</a>& ) { return FALSE; }
bool fetch( int ) { return FALSE; }
bool fetchFirst() { return FALSE; }
bool fetchLast() { return FALSE; }
bool isNull( int ) { return FALSE; }
<a href="ntqsqlrecord.html">TQSqlRecord</a> record() { return TQSqlRecord(); }
int size() { return 0; }
int numRowsAffected() { return 0; }
};
class TQNullDriver : public <a href="ntqsqldriver.html">TQSqlDriver</a>
{
public:
TQNullDriver(): <a href="ntqsqldriver.html">TQSqlDriver</a>() {}
~TQNullDriver() {}
bool hasFeature( DriverFeature ) const { return FALSE; }
bool open( const <a href="ntqstring.html">TQString</a>&,
const <a href="ntqstring.html">TQString</a>&,
const <a href="ntqstring.html">TQString</a>&,
const <a href="ntqstring.html">TQString</a>&,
int ) { return FALSE; }
void close() {}
<a href="ntqsqlquery.html">TQSqlQuery</a> createQuery() const { return TQSqlQuery( new TQNullResult( this ) ); }
};
</pre>
<p>
<!-- eof -->
<p><address><hr><div align=center>
<table width=100% cellspacing=0 border=0><tr>
<td>Copyright © 2007
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
<td align=right><div align=right>TQt 3.3.8</div>
</table></div></address></body>
</html>
|
