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<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><div class=fn><a href="#QSqlQuery"><b>QSqlQuery</b></a> ( QSqlResult * r )</div></li>
<li><div class=fn><a href="#QSqlQuery-2"><b>QSqlQuery</b></a> ( const QString & query = QString::null, QSqlDatabase * db = 0 )</div></li>
<li><div class=fn><a href="#QSqlQuery-3"><b>QSqlQuery</b></a> ( const QSqlQuery & other )</div></li>
<li><div class=fn>QSqlQuery & <a href="#operator-eq"><b>operator=</b></a> ( const QSqlQuery & other )</div></li>
<li><div class=fn>virtual <a href="#~QSqlQuery"><b>~QSqlQuery</b></a> ()</div></li>
<li><div class=fn>bool <a href="#isValid"><b>isValid</b></a> () const</div></li>
<li><div class=fn>bool <a href="#isActive"><b>isActive</b></a> () const</div></li>
<li><div class=fn>bool <a href="#isNull"><b>isNull</b></a> ( int field ) const</div></li>
<li><div class=fn>int <a href="#at"><b>at</b></a> () const</div></li>
<li><div class=fn>QString <a href="#lastQuery"><b>lastQuery</b></a> () const</div></li>
<li><div class=fn>int <a href="#numRowsAffected"><b>numRowsAffected</b></a> () const</div></li>
<li><div class=fn>QSqlError <a href="#lastError"><b>lastError</b></a> () const</div></li>
<li><div class=fn>bool <a href="#isSelect"><b>isSelect</b></a> () const</div></li>
<li><div class=fn>int <a href="#size"><b>size</b></a> () const</div></li>
<li><div class=fn>const QSqlDriver * <a href="#driver"><b>driver</b></a> () const</div></li>
<li><div class=fn>const QSqlResult * <a href="#result"><b>result</b></a> () const</div></li>
<li><div class=fn>bool <a href="#isForwardOnly"><b>isForwardOnly</b></a> () const</div></li>
<li><div class=fn>void <a href="#setForwardOnly"><b>setForwardOnly</b></a> ( bool forward )</div></li>
<li><div class=fn>virtual bool <a href="#exec"><b>exec</b></a> ( const QString & query )</div></li>
<li><div class=fn>virtual QVariant <a href="#value"><b>value</b></a> ( int i ) const</div></li>
<li><div class=fn>virtual bool <a href="#seek"><b>seek</b></a> ( int i, bool relative = FALSE )</div></li>
<li><div class=fn>virtual bool <a href="#next"><b>next</b></a> ()</div></li>
<li><div class=fn>virtual bool <a href="#prev"><b>prev</b></a> ()</div></li>
<li><div class=fn>virtual bool <a href="#first"><b>first</b></a> ()</div></li>
<li><div class=fn>virtual bool <a href="#last"><b>last</b></a> ()</div></li>
<li><div class=fn>bool <a href="#exec-2"><b>exec</b></a> ()</div></li>
<li><div class=fn>bool <a href="#prepare"><b>prepare</b></a> ( const QString & query )</div></li>
<li><div class=fn>void <a href="#bindValue"><b>bindValue</b></a> ( const QString & placeholder, const QVariant & val )</div></li>
<li><div class=fn>void <a href="#bindValue-2"><b>bindValue</b></a> ( int pos, const QVariant & val )</div></li>
<li><div class=fn>void <a href="#addBindValue"><b>addBindValue</b></a> ( const QVariant & val )</div></li>
</ul>
<h2>Protected Members</h2>
<ul>
<li><div class=fn>virtual void <a href="#beforeSeek"><b>beforeSeek</b></a> ()</div></li>
<li><div class=fn>virtual void <a href="#afterSeek"><b>afterSeek</b></a> ()</div></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. 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.
For the sake of efficiency there are no methods to access a field
by name. (The <a href="qsqlcursor.html">QSqlCursor</a> class provides a higher level
interface for that generates SQL automatically and through which
fields are accessed by name.)
<p> QSqlQuery supports prepared query execution and binding of
parameter values to placeholders. Note that only input values may
be bound. Be aware that not all databases support these
features. Currently only the Oracle and ODBC drivers have proper
prepared query support, but the rest of the drivers support this
by emulating the missing features (the placeholders are simply
replaced with the actual value when the query is executed). It is
also important to know that different databases use different
placeholder marks for value binding. Oracle uses a <tt>:</tt> character
followed by a placeholder name, while ODBC only uses a <tt>?</tt>
character to identify a placeholder. In an attempt to make this
database independant we substitute the markers if you try to use
ODBC markers in a query to an Oracle database and vice versa. Note
that you can't mix the different bind styles by binding some
values using named placeholders and some using positional
placeholders.
<p> Example:
<p> <pre>
// Named binding using named placeholders
QSqlQuery q;
q.<a href="#prepare">prepare</a>( "insert into mytable (id, name, lastname) values (:id, :name, :lname)" );
q.<a href="#bindValue">bindValue</a>( ":id", 0 );
q.<a href="#bindValue">bindValue</a>( ":name", "Testname" );
q.<a href="#bindValue">bindValue</a>( ":lname", "Lastname" );
q.<a href="#exec">exec</a>();
// Positional binding using named placeholders
QSqlQuery q;
q.<a href="#prepare">prepare</a>( "insert into mytable (id, name, lastname) values (:id, :name, :lname)" );
q.<a href="#bindValue">bindValue</a>( 0, 0 );
q.<a href="#bindValue">bindValue</a>( 1, "Testname" );
q.<a href="#bindValue">bindValue</a>( 2, "Lastname" );
q.<a href="#exec">exec</a>();
// Binding values using positional placeholders
QSqlQuery q;
q.<a href="#prepare">prepare</a>( "insert into mytable (id, name, lastname) values (?, ?, ?)" );
q.<a href="#bindValue">bindValue</a>( 0, 0 );
q.<a href="#bindValue">bindValue</a>( 1, "Testname" );
q.<a href="#bindValue">bindValue</a>( 2, "Lastname" );
q.<a href="#exec">exec</a>();
// or alternatively
q.<a href="#prepare">prepare</a>( "insert into mytable (id, name, lastname) values (?, ?, ?)" );
q.<a href="#addBindValue">addBindValue</a>( 0 );
q.<a href="#addBindValue">addBindValue</a>( "Testname" );
q.<a href="#addBindValue">addBindValue</a>( "Lastname" );
q.<a href="#exec">exec</a>();
</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.
<p> <p>See also <a href="qsqldatabase.html">QSqlDatabase</a>.
<h3 class=fn><a name="QSqlQuery-3"></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 )
</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.
Placeholder values are cleared after the query has been executed.
<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="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="#isValid">isValid</a>().
<p>Example: <a href="sql.html#x2099">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 )
</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>)
should be included when specifying the placeholder name.
Placeholder values are cleared after the query has been executed.
<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 ( 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> 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.
Placeholder values are cleared after the query has been executed.
<p> <p>See also <a href="#addBindValue">addBindValue</a>(), <a href="#prepare">prepare</a>(), and <a href="#exec">exec</a>().
<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#x2087">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2091">sql/overview/basicbrowsing2/main.cpp</a>, and <a href="sql.html#x2096">sql/overview/basicdatamanip/main.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 is 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>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>Example: <a href="sql.html#x2100">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#x2088">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2092">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2097">sql/overview/basicdatamanip/main.cpp</a>, <a href="sql.html#x2101">sql/overview/navigating/main.cpp</a>, and <a href="sql.html#x2105">sql/overview/retrieve1/main.cpp</a>.
<h3 class=fn>bool <a name="isForwardOnly"></a>QSqlQuery::isForwardOnly () const
</h3> Returns TRUE when you can only scroll forward through a result set
otherwise FALSE
<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>Example: <a href="sql.html#x2102">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.
<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="#at">at</a>() and <a href="#isValid">isValid</a>().
<p>Examples: <a href="sql.html#x2089">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2093">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2138">sql/overview/delete/main.cpp</a>, <a href="sql.html#x2113">sql/overview/order1/main.cpp</a>, <a href="sql.html#x2106">sql/overview/retrieve1/main.cpp</a>, <a href="sql.html#x2195">sql/overview/subclass4/main.cpp</a>, and <a href="sql.html#x2198">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 SELECT statements,
this value will be the same as <a href="#size">size</a>(). 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#x2094">sql/overview/basicbrowsing2/main.cpp</a> and <a href="sql.html#x2098">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. Note that placeholder
markers are usually database dependent.
<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="#at">at</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>Example: <a href="sql.html#x2103">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 have to be cached.
Forward only mode is off by default.
Note that it is not possible to use forward only mode with data aware widgets
like <a href="qdatatable.html">QDataTable</a> since they need to be able to scroll backward.
<p>See also <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 the database does not support
reporting information about query sizes. Note that for non-SELECT
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#x2104">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 "SELECT forename, surname FROM
people", field 0 is forename and field 1 is surname. 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#x2090">sql/overview/basicbrowsing/main.cpp</a>, <a href="sql.html#x2095">sql/overview/basicbrowsing2/main.cpp</a>, <a href="sql.html#x2107">sql/overview/retrieve1/main.cpp</a>, <a href="sql.html#x2192">sql/overview/subclass3/main.cpp</a>, <a href="sql.html#x2196">sql/overview/subclass4/main.cpp</a>, <a href="sql.html#x2199">sql/overview/subclass5/main.cpp</a>, and <a href="sql.html#x2182">sql/overview/table4/main.cpp</a>.
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