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| 2 | <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/sql/qsqlfield.cpp:42 -->
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| 31 | </td>
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| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QSqlField Class Reference<br><small>[<a href="sql.html">sql module</a>]</small></h1>
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| 33 |
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| 34 | <p>The QSqlField class manipulates the fields in SQL database tables
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| 35 | and views.
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| 36 | <a href="#details">More...</a>
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| 37 | <p><tt>#include <<a href="qsqlfield-h.html">qsqlfield.h</a>></tt>
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| 38 | <p><a href="qsqlfield-members.html">List of all member functions.</a>
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| 39 | <h2>Public Members</h2>
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| 40 | <ul>
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| 41 | <li class=fn><a href="#QSqlField"><b>QSqlField</b></a> ( const QString & fieldName = QString::null, QVariant::Type type = QVariant::Invalid )</li>
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| 42 | <li class=fn><a href="#QSqlField-2"><b>QSqlField</b></a> ( const QSqlField & other )</li>
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| 43 | <li class=fn>QSqlField & <a href="#operator-eq"><b>operator=</b></a> ( const QSqlField & other )</li>
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| 44 | <li class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const QSqlField & other ) const</li>
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| 45 | <li class=fn>virtual <a href="#~QSqlField"><b>~QSqlField</b></a> ()</li>
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| 46 | <li class=fn>virtual void <a href="#setValue"><b>setValue</b></a> ( const QVariant & value )</li>
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| 47 | <li class=fn>virtual QVariant <a href="#value"><b>value</b></a> () const</li>
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| 48 | <li class=fn>virtual void <a href="#setName"><b>setName</b></a> ( const QString & name )</li>
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| 49 | <li class=fn>QString <a href="#name"><b>name</b></a> () const</li>
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| 50 | <li class=fn>virtual void <a href="#setNull"><b>setNull</b></a> ()</li>
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| 51 | <li class=fn>bool <a href="#isNull"><b>isNull</b></a> () const</li>
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| 52 | <li class=fn>virtual void <a href="#setReadOnly"><b>setReadOnly</b></a> ( bool readOnly )</li>
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| 53 | <li class=fn>bool <a href="#isReadOnly"><b>isReadOnly</b></a> () const</li>
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| 54 | <li class=fn>void <a href="#clear"><b>clear</b></a> ( bool nullify = TRUE )</li>
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| 55 | <li class=fn>QVariant::Type <a href="#type"><b>type</b></a> () const</li>
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| 56 | </ul>
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| 57 | <hr><a name="details"></a><h2>Detailed Description</h2>
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| 58 |
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| 59 |
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| 60 | The QSqlField class manipulates the fields in SQL database tables
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| 61 | and views.
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| 62 | <p>
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| 63 |
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| 64 | <p> QSqlField represents the characteristics of a single column in a
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| 65 | database table or view, such as the data type and column name. A
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| 66 | field also contains the value of the database column, which can be
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| 67 | viewed or changed.
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| 68 | <p> Field data values are stored as QVariants. Using an incompatible
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| 69 | type is not permitted. For example:
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| 70 | <p> <pre>
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| 71 | QSqlField f( "myfield", QVariant::Int );
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| 72 | f.<a href="#setValue">setValue</a>( QPixmap() ); // will not work
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| 73 | </pre>
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| 74 |
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| 75 | <p> However, the field will attempt to cast certain data types to the
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| 76 | field data type where possible:
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| 77 | <p> <pre>
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| 78 | QSqlField f( "myfield", QVariant::Int );
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| 79 | f.<a href="#setValue">setValue</a>( QString("123") ); // casts QString to int
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| 80 | </pre>
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| 81 |
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| 82 | <p> QSqlField objects are rarely created explicitly in application
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| 83 | code. They are usually accessed indirectly through <a href="qsqlrecord.html">QSqlRecord</a>
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| 84 | or <a href="qsqlcursor.html">QSqlCursor</a> which already contain a list of fields. For
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| 85 | example:
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| 86 | <p> <pre>
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| 87 | <a href="qsqlcursor.html">QSqlCursor</a> cur( "Employee" ); // create cursor using the 'Employee' table
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| 88 | QSqlField* f = cur.<a href="qsqlrecord.html#field">field</a>( "name" ); // use the 'name' field
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| 89 | f-><a href="#setValue">setValue</a>( "Dave" ); // set field value
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| 90 | ...
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| 91 | </pre>
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| 92 |
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| 93 | <p> In practice we rarely need to extract a pointer to a field at all.
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| 94 | The previous example would normally be written:
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| 95 | <p> <pre>
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| 96 | <a href="qsqlcursor.html">QSqlCursor</a> cur( "Employee" );
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| 97 | cur.<a href="qsqlrecord.html#setValue">setValue</a>( "name", "Dave" );
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| 98 | ...
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| 99 | </pre>
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| 100 |
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| 101 | <p>See also <a href="database.html">Database Classes</a>.
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| 102 |
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| 103 | <hr><h2>Member Function Documentation</h2>
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| 104 | <h3 class=fn><a name="QSqlField"></a>QSqlField::QSqlField ( const <a href="qstring.html">QString</a> & fieldName = QString::null, <a href="qvariant.html#Type-enum">QVariant::Type</a> type = QVariant::Invalid )
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| 105 | </h3>
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| 106 | Constructs an empty field called <em>fieldName</em> of type <em>type</em>.
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| 107 |
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| 108 | <h3 class=fn><a name="QSqlField-2"></a>QSqlField::QSqlField ( const <a href="qsqlfield.html">QSqlField</a> & other )
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| 109 | </h3>
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| 110 | Constructs a copy of <em>other</em>.
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| 111 |
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| 112 | <h3 class=fn><a name="~QSqlField"></a>QSqlField::~QSqlField ()<tt> [virtual]</tt>
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| 113 | </h3>
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| 114 | Destroys the object and frees any allocated resources.
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| 115 |
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| 116 | <h3 class=fn>void <a name="clear"></a>QSqlField::clear ( bool nullify = TRUE )
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| 117 | </h3>
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| 118 | Clears the value of the field. If the field is read-only, nothing
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| 119 | happens. If <em>nullify</em> is TRUE (the default), the field is set to
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| 120 | NULL.
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| 121 |
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| 122 | <h3 class=fn>bool <a name="isNull"></a>QSqlField::isNull () const
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| 123 | </h3>
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| 124 |
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| 125 | <p> Returns TRUE if the field is currently NULL; otherwise returns
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| 126 | FALSE.
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| 127 |
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| 128 | <h3 class=fn>bool <a name="isReadOnly"></a>QSqlField::isReadOnly () const
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| 129 | </h3>
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| 130 |
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| 131 | <p> Returns TRUE if the field's value is read only; otherwise returns
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| 132 | FALSE.
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| 133 |
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| 134 | <h3 class=fn><a href="qstring.html">QString</a> <a name="name"></a>QSqlField::name () const
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| 135 | </h3>
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| 136 |
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| 137 | <p> Returns the name of the field.
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| 138 |
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| 139 | <p>Example: <a href="sql.html#x2249">sql/overview/table4/main.cpp</a>.
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| 140 | <h3 class=fn><a href="qsqlfield.html">QSqlField</a> & <a name="operator-eq"></a>QSqlField::operator= ( const <a href="qsqlfield.html">QSqlField</a> & other )
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| 141 | </h3>
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| 142 | Sets the field equal to <em>other</em>.
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| 143 |
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| 144 | <h3 class=fn>bool <a name="operator-eq-eq"></a>QSqlField::operator== ( const <a href="qsqlfield.html">QSqlField</a> & other ) const
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| 145 | </h3>
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| 146 | Returns TRUE if the field is equal to <em>other</em>; otherwise returns
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| 147 | FALSE. Fields are considered equal when the following field
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| 148 | properties are the same:
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| 149 | <p> <ul>
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| 150 | <li> <a href="#name">name</a>()
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| 151 | <li> <a href="#isNull">isNull</a>()
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| 152 | <li> <a href="#value">value</a>()
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| 153 | <li> <a href="#isReadOnly">isReadOnly</a>()
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| 154 | </ul>
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| 155 | <p>
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| 156 | <h3 class=fn>void <a name="setName"></a>QSqlField::setName ( const <a href="qstring.html">QString</a> & name )<tt> [virtual]</tt>
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| 157 | </h3>
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| 158 |
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| 159 | <p> Sets the name of the field to <em>name</em>.
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| 160 |
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| 161 | <h3 class=fn>void <a name="setNull"></a>QSqlField::setNull ()<tt> [virtual]</tt>
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| 162 | </h3>
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| 163 |
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| 164 | <p> Sets the field to NULL and clears the value using <a href="#clear">clear</a>(). If the
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| 165 | field is read-only, nothing happens.
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| 166 | <p> <p>See also <a href="#isReadOnly">isReadOnly</a>() and <a href="#clear">clear</a>().
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| 167 |
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| 168 | <h3 class=fn>void <a name="setReadOnly"></a>QSqlField::setReadOnly ( bool readOnly )<tt> [virtual]</tt>
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| 169 | </h3>
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| 170 |
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| 171 | <p> Sets the read only flag of the field's value to <em>readOnly</em>.
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| 172 | <p> <p>See also <a href="#setValue">setValue</a>().
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| 173 |
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| 174 | <h3 class=fn>void <a name="setValue"></a>QSqlField::setValue ( const <a href="qvariant.html">QVariant</a> & value )<tt> [virtual]</tt>
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| 175 | </h3>
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| 176 | Sets the value of the field to <em>value</em>. If the field is read-only
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| 177 | (<a href="#isReadOnly">isReadOnly</a>() returns TRUE), nothing happens. If the data type of
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| 178 | <em>value</em> differs from the field's current data type, an attempt is
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| 179 | made to cast it to the proper type. This preserves the data type
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| 180 | of the field in the case of assignment, e.g. a <a href="qstring.html">QString</a> to an
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| 181 | integer data type. For example:
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| 182 | <p> <pre>
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| 183 | <a href="qsqlcursor.html">QSqlCursor</a> cur( "Employee" ); // 'Employee' table
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| 184 | QSqlField* f = cur.<a href="qsqlrecord.html#field">field</a>( "student_count" ); // an integer field
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| 185 | ...
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| 186 | f-><a href="#setValue">setValue</a>( myLineEdit->text() ); // cast the line edit text to an integer
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| 187 | </pre>
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| 188 |
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| 189 | <p> <p>See also <a href="#isReadOnly">isReadOnly</a>().
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| 190 |
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| 191 | <h3 class=fn><a href="qvariant.html#Type-enum">QVariant::Type</a> <a name="type"></a>QSqlField::type () const
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| 192 | </h3>
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| 193 |
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| 194 | <p> Returns the field's type as stored in the database.
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| 195 | Note that the actual value might have a different type,
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| 196 | Numerical values that are too large to store in a long
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| 197 | int or double are usually stored as strings to prevent
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| 198 | precision loss.
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| 199 |
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| 200 | <h3 class=fn><a href="qvariant.html">QVariant</a> <a name="value"></a>QSqlField::value () const<tt> [virtual]</tt>
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| 201 | </h3>
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| 202 |
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| 203 | <p> Returns the value of the field as a <a href="qvariant.html">QVariant</a>.
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| 204 |
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| 205 | <p>Example: <a href="sql.html#x2250">sql/overview/table4/main.cpp</a>.
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| 206 | <!-- eof -->
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| 207 | <hr><p>
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| 208 | This file is part of the <a href="index.html">Qt toolkit</a>.
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| 209 | Copyright © 1995-2007
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| 210 | <a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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| 211 | <table width=100% cellspacing=0 border=0><tr>
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| 212 | <td>Copyright © 2007
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| 213 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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| 214 | <td align=right><div align=right>Qt 3.3.8</div>
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| 215 | </table></div></address></body>
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| 216 | </html>
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