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
|
<!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/src/sql/qsqlquery.cpp:79 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>QSqlQuery Class</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>QSqlQuery Class Reference<br><small>[<a href="sql.html">sql module</a>]</small></h1>
<p>The QSqlQuery class provides a means of executing and
manipulating SQL statements.
<a href="#details">More...</a>
<p><tt>#include <<a href="qsqlquery-h.html">qsqlquery.h</a>></tt>
<p>Inherited by <a href="qsqlcursor.html">QSqlCursor</a>.
<p><a href="qsqlquery-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li class=fn><a href="#QSqlQuery"><b>QSqlQuery</b></a> ( QSqlResult * r )</li>
<li class=fn><a href="#QSqlQuery-2"><b>QSqlQuery</b></a> ( const QString & query = QString::null, QSqlDatabase * db = 0 )</li>
<li class=fn>explicit <a href="#QSqlQuery-3"><b>QSqlQuery</b></a> ( QSqlDatabase * db )</li>
<li class=fn><a href="#QSqlQuery-4"><b>QSqlQuery</b></a> ( const QSqlQuery & other )</li>
<li class=fn>QSqlQuery & <a href="#operator-eq"><b>operator=</b></a> ( const QSqlQuery & other )</li>
<li class=fn>virtual <a href="#~QSqlQuery"><b>~QSqlQuery</b></a> ()</li>
<li class=fn>bool <a href="#isValid"><b>isValid</b></a> () const</li>
<li class=fn>bool <a href="#isActive"><b>isActive</b></a> () const</li>
<li class=fn>bool <a href="#isNull"><b>isNull</b></a> ( int field ) const</li>
<li class=fn>int <a href="#at"><b>at</b></a> () const</li>
<li class=fn>QString <a href="#lastQuery"><b>lastQuery</b></a> () const</li>
<li class=fn>int <a href="#numRowsAffected"><b>numRowsAffected</b></a> () const</li>
<li class=fn>QSqlError <a href="#lastError"><b>lastError</b></a> () const</li>
<li class=fn>bool <a href="#isSelect"><b>isSelect</b></a> () const</li>
<li class=fn>int <a href="#size"><b>size</b></a> () const</li>
<li class=fn>const QSqlDriver * <a href="#driver"><b>driver</b></a> () const</li>
<li class=fn>const QSqlResult * <a href="#result"><b>result</b></a> () const</li>
<li class=fn>bool <a href="#isForwardOnly"><b>isForwardOnly</b></a> () const</li>
<li class=fn>void <a href="#setForwardOnly"><b>setForwardOnly</b></a> ( bool forward )</li>
<li class=fn>virtual bool <a href="#exec"><b>exec</b></a> ( const QString & query )</li>
<li class=fn>virtual QVariant <a href="#value"><b>value</b></a> ( int i ) const</li>
<li class=fn>virtual bool <a href="#seek"><b>seek</b></a> ( int i, bool relative = FALSE )</li>
<li class=fn>virtual bool <a href="#next"><b>next</b></a> ()</li>
<li class=fn>virtual bool <a href="#prev"><b>prev</b></a> ()</li>
<li class=fn>virtual bool <a href="#first"><b>first</b></a> ()</li>
<li class=fn>virtual bool <a href="#last"><b>last</b></a> ()</li>
<li class=fn>bool <a href="#exec-2"><b>exec</b></a> ()</li>
<li class=fn>bool <a href="#prepare"><b>prepare</b></a> ( const QString & query )</li>
<li class=fn>void <a href="#bindValue-2"><b>bindValue</b></a> ( const QString & placeholder, const QVariant & val )</li>
<li class=fn>void <a href="#bindValue-3"><b>bindValue</b></a> ( int pos, const QVariant & val )</li>
<li class=fn>void <a href="#addBindValue-2"><b>addBindValue</b></a> ( const QVariant & val )</li>
<li class=fn>void <a href="#bindValue"><b>bindValue</b></a> ( const QString & placeholder, const QVariant & val, QSql::ParameterType type )</li>
<li class=fn>void <a href="#bindValue-4"><b>bindValue</b></a> ( int pos, const QVariant & val, QSql::ParameterType type )</li>
<li class=fn>void <a href="#addBindValue"><b>addBindValue</b></a> ( const QVariant & val, QSql::ParameterType type )</li>
<li class=fn>QVariant <a href="#boundValue"><b>boundValue</b></a> ( const QString & placeholder ) const</li>
<li class=fn>QVariant <a href="#boundValue-2"><b>boundValue</b></a> ( int pos ) const</li>
<li class=fn>QMap<QString, QVariant> <a href="#boundValues"><b>boundValues</b></a> () const</li>
<li class=fn>QString <a href="#executedQuery"><b>executedQuery</b></a> () const</li>
</ul>
<h2>Protected Members</h2>
<ul>
<li class=fn>virtual void <a href="#beforeSeek"><b>beforeSeek</b></a> ()</li>
<li class=fn>virtual void <a href="#afterSeek"><b>afterSeek</b></a> ()</li>
</ul>
<hr><a name="details"></a><h2>Detailed Description</h2>
The QSqlQuery class provides a means of executing and
manipulating SQL statements.
<p>
<p> QSqlQuery encapsulates the functionality involved in creating,
navigating and retrieving data from SQL queries which are executed
on a <a href="qsqldatabase.html">QSqlDatabase</a>. It can be used to execute DML (data
manipulation language) statements, e.g. <tt>SELECT</tt>, <tt>INSERT</tt>, <tt>UPDATE</tt> and <tt>DELETE</tt>, and also DDL (data definition language)
statements, e.g. <tt>CREATE TABLE</tt>. It can also be used to
execute database-specific commands which are not standard SQL
(e.g. <tt>SET DATESTYLE=ISO</tt> for PostgreSQL).
<p> Successfully executed SQL statements set the query's state to
active (<a href="#isActive">isActive</a>() returns TRUE); otherwise the query's state is
set to inactive. In either case, when executing a new SQL
statement, the query is positioned on an invalid record; an active
query must be navigated to a valid record (so that <a href="#isValid">isValid</a>()
returns TRUE) before values can be retrieved.
<p> Navigating records is performed with the following functions:
<p> <ul>
<li> <a href="#next">next</a>()
<li> <a href="#prev">prev</a>()
<li> <a href="#first">first</a>()
<li> <a href="#last">last</a>()
<li> <tt></tt><a href="#seek">seek</a>(int)
</ul>
<p> These functions allow the programmer to move forward, backward or
arbitrarily through the records returned by the query. If you only
need to move forward through the results, e.g. using <a href="#next">next</a>() or
using <a href="#seek">seek</a>() with a positive offset, you can use <a href="#setForwardOnly">setForwardOnly</a>()
and save a significant amount of memory overhead. Once an active
query is positioned on a valid record, data can be retrieved using
<a href="#value">value</a>(). All data is transferred from the SQL backend using
QVariants.
<p> For example:
<p> <pre>
QSqlQuery query( "SELECT name FROM customer" );
while ( query.<a href="#next">next</a>() ) {
<a href="qstring.html">QString</a> name = query.<a href="#value">value</a>(0).toString();
doSomething( name );
}
</pre>
<p> To access the data returned by a query, use the value() method.
Each field in the data returned by a SELECT statement is accessed
by passing the field's position in the statement, starting from 0.
Information about the fields can be obtained via <a href="qsqldatabase.html#record">QSqlDatabase::record</a>().
For the sake of efficiency there are no functions to access a field
by name. (The <a href="qsqlcursor.html">QSqlCursor</a> class provides a higher-level interface
with field access by name and automatic SQL generation.)
<p> QSqlQuery supports prepared query execution and the binding of
parameter values to placeholders. Some databases don't support
these features, so for them Qt emulates the required
functionality. For example, the Oracle and ODBC drivers have
proper prepared query support, and Qt makes use of it; but for
databases that don't have this support, Qt implements the feature
itself, e.g. by replacing placeholders with actual values when a
query is executed. The exception is positional binding using named
placeholders, which requires that the database supports prepared
queries.
<p> Oracle databases identify placeholders by using a colon-name
syntax, e.g <tt>:name</tt>. ODBC simply uses <tt>?</tt> characters. Qt
supports both syntaxes (although you can't mix them in the same
query).
<p> Below we present the same example using each of the four different
binding approaches.
<p> <b>Named binding using named placeholders</b>
<pre>
QSqlQuery query;
query.<a href="#prepare">prepare</a>( "INSERT INTO atable (id, forename, surname) "
"VALUES (:id, :forename, :surname)" );
query.<a href="#bindValue">bindValue</a>( ":id", 1001 );
query.<a href="#bindValue">bindValue</a>( ":forename", "Bart" );
query.<a href="#bindValue">bindValue</a>( ":surname", "Simpson" );
query.<a href="#exec">exec</a>();
</pre>
<p> <b>Positional binding using named placeholders</b>
<pre>
QSqlQuery query;
query.<a href="#prepare">prepare</a>( "INSERT INTO atable (id, forename, surname) "
"VALUES (:id, :forename, :surname)" );
query.<a href="#bindValue">bindValue</a>( 0, 1001 );
query.<a href="#bindValue">bindValue</a>( 1, "Bart" );
query.<a href="#bindValue">bindValue</a>( 2, "Simpson" );
query.<a href="#exec">exec</a>();
</pre>
<b>Note:</b> Using positional binding with named placeholders will
only work if the database supports prepared queries. This can be
checked with <a href="qsqldriver.html#hasFeature">QSqlDriver::hasFeature</a>() using QSqlDriver::PreparedQueries
as argument for driver feature.
<p> <b>Binding values using positional placeholders #1</b>
<pre>
QSqlQuery query;
query.<a href="#prepare">prepare</a>( "INSERT INTO atable (id, forename, surname) "
"VALUES (?, ?, ?)" );
query.<a href="#bindValue">bindValue</a>( 0, 1001 );
query.<a href="#bindValue">bindValue</a>( 1, "Bart" );
query.<a href="#bindValue">bindValue</a>( 2, "Simpson" );
query.<a href="#exec">exec</a>();
</pre>
<p> <b>Binding values using positional placeholders #2</b>
<pre>
query.prepare( "INSERT INTO atable (id, forename, surname) "
"VALUES (?, ?, ?)" );
query.addBindValue( 1001 );
query.addBindValue( "Bart" );
query.addBindValue( "Simpson" );
query.exec();
</pre>
<p> <b>Binding values to a stored procedure</b>
This code calls a stored procedure called <tt>AsciiToInt()</tt>, passing
it a character through its in parameter, and taking its result in
the out parameter.
<pre>
QSqlQuery query;
query.<a href="#prepare">prepare</a>( "call AsciiToInt(?, ?)" );
query.<a href="#bindValue">bindValue</a>( 0, "A" );
query.<a href="#bindValue">bindValue</a>( 1, 0, QSql::Out );
query.<a href="#exec">exec</a>();
int i = query.<a href="#boundValue">boundValue</a>( 1 ).toInt(); // i is 65.
</pre>
<p> <p>See also <a href="qsqldatabase.html">QSqlDatabase</a>, <a href="qsqlcursor.html">QSqlCursor</a>, <a href="qvariant.html">QVariant</a>, and <a href="database.html">Database Classes</a>.
<hr><h2>Member Function Documentation</h2>
<h3 class=fn><a name="QSqlQuery"></a>QSqlQuery::QSqlQuery ( <a href="qsqlresult.html">QSqlResult</a> * r )
</h3>
Creates a QSqlQuery object which uses the <a href="qsqlresult.html">QSqlResult</a> <em>r</em> to
communicate with a database.
<h3 class=fn><a name="QSqlQuery-2"></a>QSqlQuery::QSqlQuery ( const <a href="qstring.html">QString</a> & query = QString::null, <a href="qsqldatabase.html">QSqlDatabase</a> * db = 0 )
</h3>
Creates a QSqlQuery object using the SQL <em>query</em> and the database
<em>db</em>. If <em>db</em> is 0, (the default), the application's default
database is used. If <em>query</em> is not a null string, it will be
executed.
<p> <p>See also <a href="qsqldatabase.html">QSqlDatabase</a>.
<h3 class=fn>explicit <a name="QSqlQuery-3"></a>QSqlQuery::QSqlQuery ( <a href="qsqldatabase.html">QSqlDatabase</a> * db )
</h3>
Creates a QSqlQuery object using the database <em>db</em>. If <em>db</em> is
0, the application's default database is used.
<p> <p>See also <a href="qsqldatabase.html">QSqlDatabase</a>.
<h3 class=fn><a name="QSqlQuery-4"></a>QSqlQuery::QSqlQuery ( const <a href="qsqlquery.html">QSqlQuery</a> & other )
</h3>
Constructs a copy of <em>other</em>.
<h3 class=fn><a name="~QSqlQuery"></a>QSqlQuery::~QSqlQuery ()<tt> [virtual]</tt>
</h3>
Destroys the object and frees any allocated resources.
<h3 class=fn>void <a name="addBindValue"></a>QSqlQuery::addBindValue ( const <a href="qvariant.html">QVariant</a> & val, <a href="qsql.html#ParameterType-enum">QSql::ParameterType</a> type )
</h3>
Adds the value <em>val</em> to the list of values when using positional
value binding. The order of the <a href="#addBindValue">addBindValue</a>() calls determines
which placeholder a value will be bound to in the prepared query.
If <em>type</em> is <a href="qsql.html#ParameterType-enum">QSql::Out</a> or <a href="qsql.html#ParameterType-enum">QSql::InOut</a>, the placeholder will
be overwritten with data from the database after the <a href="#exec">exec</a>() call.
<p> <p>See also <a href="#bindValue">bindValue</a>(), <a href="#prepare">prepare</a>(), and <a href="#exec">exec</a>().
<h3 class=fn>void <a name="addBindValue-2"></a>QSqlQuery::addBindValue ( const <a href="qvariant.html">QVariant</a> & val )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Binds the placeholder with type <a href="qsql.html#ParameterType-enum">QSql::In</a>.
<h3 class=fn>void <a name="afterSeek"></a>QSqlQuery::afterSeek ()<tt> [virtual protected]</tt>
</h3>
Protected virtual function called after the internal record
pointer is moved to a new record. The default implementation does
nothing.
<h3 class=fn>int <a name="at"></a>QSqlQuery::at () const
</h3>
Returns the current internal position of the query. The first
record is at position zero. If the position is invalid, a
QSql::Location will be returned indicating the invalid position.
<p> <p>See also <a href="#prev">prev</a>(), <a href="#next">next</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), <a href="#seek">seek</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Example: <a href="sql.html#x2169">sql/overview/navigating/main.cpp</a>.
<h3 class=fn>void <a name="beforeSeek"></a>QSqlQuery::beforeSeek ()<tt> [virtual protected]</tt>
</h3>
Protected virtual function called before the internal record
pointer is moved to a new record. The default implementation does
nothing.
<h3 class=fn>void <a name="bindValue"></a>QSqlQuery::bindValue ( const <a href="qstring.html">QString</a> & placeholder, const <a href="qvariant.html">QVariant</a> & val, <a href="qsql.html#ParameterType-enum">QSql::ParameterType</a> type )
</h3>
Set the placeholder <em>placeholder</em> to be bound to value <em>val</em> in
the prepared statement. Note that the placeholder mark (e.g <tt>:</tt>)
must be included when specifying the placeholder name. If <em>type</em>
is <a href="qsql.html#ParameterType-enum">QSql::Out</a> or <a href="qsql.html#ParameterType-enum">QSql::InOut</a>, the placeholder will be
overwritten with data from the database after the <a href="#exec">exec</a>() call.
<p> <p>See also <a href="#addBindValue">addBindValue</a>(), <a href="#prepare">prepare</a>(), and <a href="#exec">exec</a>().
<h3 class=fn>void <a name="bindValue-2"></a>QSqlQuery::bindValue ( const <a href="qstring.html">QString</a> & placeholder, const <a href="qvariant.html">QVariant</a> & val )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Binds the placeholder with type <a href="qsql.html#ParameterType-enum">QSql::In</a>.
<h3 class=fn>void <a name="bindValue-3"></a>QSqlQuery::bindValue ( int pos, const <a href="qvariant.html">QVariant</a> & val )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Binds the placeholder at position <em>pos</em> with type <a href="qsql.html#ParameterType-enum">QSql::In</a>.
<h3 class=fn>void <a name="bindValue-4"></a>QSqlQuery::bindValue ( int pos, const <a href="qvariant.html">QVariant</a> & val, <a href="qsql.html#ParameterType-enum">QSql::ParameterType</a> type )
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Set the placeholder in position <em>pos</em> to be bound to value <em>val</em>
in the prepared statement. Field numbering starts at 0. If <em>type</em>
is <a href="qsql.html#ParameterType-enum">QSql::Out</a> or <a href="qsql.html#ParameterType-enum">QSql::InOut</a>, the placeholder will be
overwritten with data from the database after the <a href="#exec">exec</a>() call.
<p> <p>See also <a href="#addBindValue">addBindValue</a>(), <a href="#prepare">prepare</a>(), and <a href="#exec">exec</a>().
<h3 class=fn><a href="qvariant.html">QVariant</a> <a name="boundValue"></a>QSqlQuery::boundValue ( const <a href="qstring.html">QString</a> & placeholder ) const
</h3>
Returns the value for the <em>placeholder</em>.
<h3 class=fn><a href="qvariant.html">QVariant</a> <a name="boundValue-2"></a>QSqlQuery::boundValue ( int pos ) const
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Returns the value for the placeholder at position <em>pos</em>.
<h3 class=fn><a href="qmap.html">QMap</a><QString, QVariant> <a name="boundValues"></a>QSqlQuery::boundValues () const
</h3>
Returns a map of the bound values.
<p> The bound values can be examined in the following way:
<pre>
QSqlQuery query;
...
// Examine the bound values - bound using named binding
QMap<QString, QVariant>::ConstIterator it;
<a href="qmap.html">QMap</a><QString, QVariant> vals = query.<a href="#boundValues">boundValues</a>();
for ( it = vals.<a href="qmap.html#begin">begin</a>(); it != vals.<a href="qmap.html#end">end</a>(); ++it )
<a href="qapplication.html#qWarning">qWarning</a>( "Placeholder: " + it.key() + ", Value: " + (*it).toString() );
...
// Examine the bound values - bound using positional binding
QValueList<QVariant>::ConstIterator it;
<a href="qvaluelist.html">QValueList</a><QVariant> list = query.<a href="#boundValues">boundValues</a>().values();
int i = 0;
for ( it = list.<a href="qvaluelist.html#begin">begin</a>(); it != list.<a href="qvaluelist.html#end">end</a>(); ++it )
<a href="qapplication.html#qWarning">qWarning</a>( "Placeholder pos: %d, Value: " + (*it).toString(), i++ );
...
</pre>
<h3 class=fn>const <a href="qsqldriver.html">QSqlDriver</a> * <a name="driver"></a>QSqlQuery::driver () const
</h3>
Returns the database driver associated with the query.
<h3 class=fn>bool <a name="exec"></a>QSqlQuery::exec ( const <a href="qstring.html">QString</a> & query )<tt> [virtual]</tt>
</h3>
Executes the SQL in <em>query</em>. Returns TRUE and sets the query
state to active if the query was successful; otherwise returns
FALSE and sets the query state to inactive. The <em>query</em> string
must use syntax appropriate for the SQL database being queried,
for example, standard SQL.
<p> After the query is executed, the query is positioned on an <em>invalid</em> record, and must be navigated to a valid record before
data values can be retrieved, e.g. using <a href="#next">next</a>().
<p> Note that the last error for this query is reset when <a href="#exec">exec</a>() is
called.
<p> <p>See also <a href="#isActive">isActive</a>(), <a href="#isValid">isValid</a>(), <a href="#next">next</a>(), <a href="#prev">prev</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), and <a href="#seek">seek</a>().
<p>Examples: <a href="sql.html#x2157">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2161">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2166">sql/overview/basicdatamanip/main.cpp</a>, and <a href="sql.html#x2154">sql/overview/connection.cpp</a>.
<h3 class=fn>bool <a name="exec-2"></a>QSqlQuery::exec ()
</h3>
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
<p> Executes a previously prepared SQL query. Returns TRUE if the
query executed successfully; otherwise returns FALSE.
<p> <p>See also <a href="#prepare">prepare</a>(), <a href="#bindValue">bindValue</a>(), and <a href="#addBindValue">addBindValue</a>().
<h3 class=fn><a href="qstring.html">QString</a> <a name="executedQuery"></a>QSqlQuery::executedQuery () const
</h3>
Returns the last query that was executed.
<p> In most cases this function returns the same as <a href="#lastQuery">lastQuery</a>(). If a
prepared query with placeholders is executed on a DBMS that does
not support it, the preparation of this query is emulated. The
placeholders in the original query are replaced with their bound
values to form a new query. This function returns the modified
query. Useful for debugging purposes.
<p> <p>See also <a href="#lastQuery">lastQuery</a>().
<h3 class=fn>bool <a name="first"></a>QSqlQuery::first ()<tt> [virtual]</tt>
</h3>
Retrieves the first record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in an active state and <a href="#isSelect">isSelect</a>() must return TRUE before
calling this function or it will do nothing and return FALSE.
Returns TRUE if successful. If unsuccessful the query position is
set to an invalid position and FALSE is returned.
<p> <p>See also <a href="#next">next</a>(), <a href="#prev">prev</a>(), <a href="#last">last</a>(), <a href="#seek">seek</a>(), <a href="#at">at</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Example: <a href="sql.html#x2170">sql/overview/navigating/main.cpp</a>.
<h3 class=fn>bool <a name="isActive"></a>QSqlQuery::isActive () const
</h3>
Returns TRUE if the query is currently active; otherwise returns
FALSE.
<p>Examples: <a href="sql.html#x2158">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2162">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2167">sql/overview/basicdatamanip/main.cpp</a>, <a href="sql.html#x2171">sql/overview/navigating/main.cpp</a>, and <a href="sql.html#x2175">sql/overview/retrieve1/main.cpp</a>.
<h3 class=fn>bool <a name="isForwardOnly"></a>QSqlQuery::isForwardOnly () const
</h3>
Returns TRUE if you can only scroll <em>forward</em> through a result
set; otherwise returns FALSE.
<p> <p>See also <a href="#setForwardOnly">setForwardOnly</a>().
<h3 class=fn>bool <a name="isNull"></a>QSqlQuery::isNull ( int field ) const
</h3>
Returns TRUE if the query is active and positioned on a valid
record and the <em>field</em> is NULL; otherwise returns FALSE. Note
that for some drivers <a href="#isNull">isNull</a>() will not return accurate
information until after an attempt is made to retrieve data.
<p> <p>See also <a href="#isActive">isActive</a>(), <a href="#isValid">isValid</a>(), and <a href="#value">value</a>().
<h3 class=fn>bool <a name="isSelect"></a>QSqlQuery::isSelect () const
</h3>
Returns TRUE if the current query is a <tt>SELECT</tt> statement;
otherwise returns FALSE.
<h3 class=fn>bool <a name="isValid"></a>QSqlQuery::isValid () const
</h3>
Returns TRUE if the query is currently positioned on a valid
record; otherwise returns FALSE.
<h3 class=fn>bool <a name="last"></a>QSqlQuery::last ()<tt> [virtual]</tt>
</h3>
Retrieves the last record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in an active state and <a href="#isSelect">isSelect</a>() must return TRUE before
calling this function or it will do nothing and return FALSE.
Returns TRUE if successful. If unsuccessful the query position is
set to an invalid position and FALSE is returned.
<p> <p>See also <a href="#next">next</a>(), <a href="#prev">prev</a>(), <a href="#first">first</a>(), <a href="#seek">seek</a>(), <a href="#at">at</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Example: <a href="sql.html#x2172">sql/overview/navigating/main.cpp</a>.
<h3 class=fn><a href="qsqlerror.html">QSqlError</a> <a name="lastError"></a>QSqlQuery::lastError () const
</h3>
Returns error information about the last error (if any) that
occurred.
<p> <p>See also <a href="qsqlerror.html">QSqlError</a>.
<h3 class=fn><a href="qstring.html">QString</a> <a name="lastQuery"></a>QSqlQuery::lastQuery () const
</h3>
Returns the text of the current query being used, or <a href="qstring.html#QString-null">QString::null</a>
if there is no current query text.
<p> <p>See also <a href="#executedQuery">executedQuery</a>().
<h3 class=fn>bool <a name="next"></a>QSqlQuery::next ()<tt> [virtual]</tt>
</h3>
Retrieves the next record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in an active state and <a href="#isSelect">isSelect</a>() must return TRUE before
calling this function or it will do nothing and return FALSE.
<p> The following rules apply:
<p> <ul>
<li> If the result is currently located before the first
record, e.g. immediately after a query is executed, an attempt is
made to retrieve the first record.
<p> <li> If the result is currently located after the last record,
there is no change and FALSE is returned.
<p> <li> If the result is located somewhere in the middle, an attempt
is made to retrieve the next record.
</ul>
<p> If the record could not be retrieved, the result is positioned after
the last record and FALSE is returned. If the record is successfully
retrieved, TRUE is returned.
<p> <p>See also <a href="#prev">prev</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), <a href="#seek">seek</a>(), <a href="#at">at</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Examples: <a href="sql.html#x2159">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2163">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2208">sql/overview/delete/main.cpp</a>, <a href="sql.html#x2183">sql/overview/order1/main.cpp</a>, <a href="sql.html#x2176">sql/overview/retrieve1/main.cpp</a>, <a href="sql.html#x2265">sql/overview/subclass4/main.cpp</a>, and <a href="sql.html#x2268">sql/overview/subclass5/main.cpp</a>.
<h3 class=fn>int <a name="numRowsAffected"></a>QSqlQuery::numRowsAffected () const
</h3>
Returns the number of rows affected by the result's SQL statement,
or -1 if it cannot be determined. Note that for <tt>SELECT</tt>
statements, the value is undefined; see <a href="#size">size</a>() instead. If the
query is not active (<a href="#isActive">isActive</a>() returns FALSE), -1 is returned.
<p> <p>See also <a href="#size">size</a>() and <a href="qsqldriver.html#hasFeature">QSqlDriver::hasFeature</a>().
<p>Examples: <a href="sql.html#x2164">sql/overview/basicbrowsing2/main.cpp</a> and <a href="sql.html#x2168">sql/overview/basicdatamanip/main.cpp</a>.
<h3 class=fn><a href="qsqlquery.html">QSqlQuery</a> & <a name="operator-eq"></a>QSqlQuery::operator= ( const <a href="qsqlquery.html">QSqlQuery</a> & other )
</h3>
Assigns <em>other</em> to the query.
<h3 class=fn>bool <a name="prepare"></a>QSqlQuery::prepare ( const <a href="qstring.html">QString</a> & query )
</h3>
Prepares the SQL query <em>query</em> for execution. The query may
contain placeholders for binding values. Both Oracle style
colon-name (e.g. <tt>:surname</tt>), and ODBC style (e.g. <tt>?</tt>)
placeholders are supported; but they cannot be mixed in the same
query. See the <a href="#details">Description</a> for examples.
<p> <p>See also <a href="#exec">exec</a>(), <a href="#bindValue">bindValue</a>(), and <a href="#addBindValue">addBindValue</a>().
<h3 class=fn>bool <a name="prev"></a>QSqlQuery::prev ()<tt> [virtual]</tt>
</h3>
Retrieves the previous record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in an active state and <a href="#isSelect">isSelect</a>() must return TRUE before
calling this function or it will do nothing and return FALSE.
<p> The following rules apply:
<p> <ul>
<li> If the result is currently located before the first record,
there is no change and FALSE is returned.
<p> <li> If the result is currently located after the last record, an
attempt is made to retrieve the last record.
<p> <li> If the result is somewhere in the middle, an attempt is made
to retrieve the previous record.
</ul>
<p> If the record could not be retrieved, the result is positioned
before the first record and FALSE is returned. If the record is
successfully retrieved, TRUE is returned.
<p> <p>See also <a href="#next">next</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), <a href="#seek">seek</a>(), <a href="#at">at</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<h3 class=fn>const <a href="qsqlresult.html">QSqlResult</a> * <a name="result"></a>QSqlQuery::result () const
</h3>
Returns the result associated with the query.
<h3 class=fn>bool <a name="seek"></a>QSqlQuery::seek ( int i, bool relative = FALSE )<tt> [virtual]</tt>
</h3>
Retrieves the record at position (offset) <em>i</em>, if available, and
positions the query on the retrieved record. The first record is
at position 0. Note that the query must be in an active state and
<a href="#isSelect">isSelect</a>() must return TRUE before calling this function.
<p> If <em>relative</em> is FALSE (the default), the following rules apply:
<p> <ul>
<li> If <em>i</em> is negative, the result is positioned before the
first record and FALSE is returned.
<li> Otherwise, an attempt is made to move to the record at position
<em>i</em>. If the record at position <em>i</em> could not be retrieved, the
result is positioned after the last record and FALSE is returned. If
the record is successfully retrieved, TRUE is returned.
</ul>
<p> If <em>relative</em> is TRUE, the following rules apply:
<p> <ul>
<li> If the result is currently positioned before the first
record or on the first record, and <em>i</em> is negative, there is no
change, and FALSE is returned.
<li> If the result is currently located after the last record, and
<em>i</em> is positive, there is no change, and FALSE is returned.
<li> If the result is currently located somewhere in the middle,
and the relative offset <em>i</em> moves the result below zero, the
result is positioned before the first record and FALSE is
returned.
<li> Otherwise, an attempt is made to move to the record <em>i</em>
records ahead of the current record (or <em>i</em> records behind the
current record if <em>i</em> is negative). If the record at offset <em>i</em>
could not be retrieved, the result is positioned after the last
record if <em>i</em> >= 0, (or before the first record if <em>i</em> is
negative), and FALSE is returned. If the record is successfully
retrieved, TRUE is returned.
</ul>
<p> <p>See also <a href="#next">next</a>(), <a href="#prev">prev</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), <a href="#at">at</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Example: <a href="sql.html#x2173">sql/overview/navigating/main.cpp</a>.
<h3 class=fn>void <a name="setForwardOnly"></a>QSqlQuery::setForwardOnly ( bool forward )
</h3>
Sets forward only mode to <em>forward</em>. If forward is TRUE only
<a href="#next">next</a>(), and <a href="#seek">seek</a>() with positive values, are allowed for
navigating the results. Forward only mode needs far less memory
since results do not need to be cached.
<p> Forward only mode is off by default.
<p> Forward only mode cannot be used with data aware widgets like
<a href="qdatatable.html">QDataTable</a>, since they must to be able to scroll backward as well
as forward.
<p> <p>See also <a href="#isForwardOnly">isForwardOnly</a>(), <a href="#next">next</a>(), and <a href="#seek">seek</a>().
<h3 class=fn>int <a name="size"></a>QSqlQuery::size () const
</h3>
Returns the size of the result, (number of rows returned), or -1
if the size cannot be determined or if the database does not
support reporting information about query sizes. Note that for
non-<tt>SELECT</tt> statements (<a href="#isSelect">isSelect</a>() returns FALSE), <a href="#size">size</a>() will
return -1. If the query is not active (<a href="#isActive">isActive</a>() returns FALSE),
-1 is returned.
<p> To determine the number of rows affected by a non-SELECT
statement, use <a href="#numRowsAffected">numRowsAffected</a>().
<p> <p>See also <a href="#isActive">isActive</a>(), <a href="#numRowsAffected">numRowsAffected</a>(), and <a href="qsqldriver.html#hasFeature">QSqlDriver::hasFeature</a>().
<p>Example: <a href="sql.html#x2174">sql/overview/navigating/main.cpp</a>.
<h3 class=fn><a href="qvariant.html">QVariant</a> <a name="value"></a>QSqlQuery::value ( int i ) const<tt> [virtual]</tt>
</h3>
Returns the value of the <em>i</em>-th field in the query (zero based).
<p> The fields are numbered from left to right using the text of the
<tt>SELECT</tt> statement, e.g. in <tt>SELECT forename, surname FROM people</tt>,
field 0 is <tt>forename</tt> and field 1 is <tt>surname</tt>. Using <tt>SELECT *</tt>
is not recommended because the order of the fields in the query is
undefined.
<p> An invalid <a href="qvariant.html">QVariant</a> is returned if field <em>i</em> does not exist, if
the query is inactive, or if the query is positioned on an invalid
record.
<p> <p>See also <a href="#prev">prev</a>(), <a href="#next">next</a>(), <a href="#first">first</a>(), <a href="#last">last</a>(), <a href="#seek">seek</a>(), <a href="#isActive">isActive</a>(), and <a href="#isValid">isValid</a>().
<p>Examples: <a href="sql.html#x2160">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2165">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2177">sql/overview/retrieve1/main.cpp</a>, <a href="sql.html#x2262">sql/overview/subclass3/main.cpp</a>, <a href="sql.html#x2266">sql/overview/subclass4/main.cpp</a>, <a href="sql.html#x2269">sql/overview/subclass5/main.cpp</a>, and <a href="sql.html#x2252">sql/overview/table4/main.cpp</a>.
<!-- eof -->
<hr><p>
This file is part of the <a href="index.html">Qt toolkit</a>.
Copyright © 1995-2007
<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<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>Qt 3.3.8</div>
</table></div></address></body>
</html>
|
