You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
217 lines
9.7 KiB
217 lines
9.7 KiB
13 years ago
|
<!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/qsqlfield.cpp:42 -->
|
||
|
|
<html>
|
||
|
|
<head>
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||
|
|
<title>TQSqlField 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>TQSqlField Class Reference<br><small>[<a href="sql.html">sql module</a>]</small></h1>
|
||
|
|
|
||
|
|
<p>The TQSqlField class manipulates the fields in SQL database tables
|
||
|
|
and views.
|
||
|
|
<a href="#details">More...</a>
|
||
|
|
<p><tt>#include <<a href="qsqlfield-h.html">qsqlfield.h</a>></tt>
|
||
|
|
<p><a href="qsqlfield-members.html">List of all member functions.</a>
|
||
|
|
<h2>Public Members</h2>
|
||
|
|
<ul>
|
||
|
|
<li class=fn><a href="#TQSqlField"><b>TQSqlField</b></a> ( const TQString & fieldName = TQString::null, TQVariant::Type type = TQVariant::Invalid )</li>
|
||
|
|
<li class=fn><a href="#TQSqlField-2"><b>TQSqlField</b></a> ( const TQSqlField & other )</li>
|
||
|
|
<li class=fn>TQSqlField & <a href="#operator-eq"><b>operator=</b></a> ( const TQSqlField & other )</li>
|
||
|
|
<li class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const TQSqlField & other ) const</li>
|
||
|
|
<li class=fn>virtual <a href="#~TQSqlField"><b>~TQSqlField</b></a> ()</li>
|
||
|
|
<li class=fn>virtual void <a href="#setValue"><b>setValue</b></a> ( const TQVariant & value )</li>
|
||
|
|
<li class=fn>virtual TQVariant <a href="#value"><b>value</b></a> () const</li>
|
||
|
|
<li class=fn>virtual void <a href="#setName"><b>setName</b></a> ( const TQString & name )</li>
|
||
|
|
<li class=fn>TQString <a href="#name"><b>name</b></a> () const</li>
|
||
|
|
<li class=fn>virtual void <a href="#setNull"><b>setNull</b></a> ()</li>
|
||
|
|
<li class=fn>bool <a href="#isNull"><b>isNull</b></a> () const</li>
|
||
|
|
<li class=fn>virtual void <a href="#setReadOnly"><b>setReadOnly</b></a> ( bool readOnly )</li>
|
||
|
|
<li class=fn>bool <a href="#isReadOnly"><b>isReadOnly</b></a> () const</li>
|
||
|
|
<li class=fn>void <a href="#clear"><b>clear</b></a> ( bool nullify = TRUE )</li>
|
||
|
|
<li class=fn>TQVariant::Type <a href="#type"><b>type</b></a> () const</li>
|
||
|
|
</ul>
|
||
|
|
<hr><a name="details"></a><h2>Detailed Description</h2>
|
||
|
|
|
||
|
|
|
||
|
|
The TQSqlField class manipulates the fields in SQL database tables
|
||
|
|
and views.
|
||
|
|
<p>
|
||
|
|
|
||
|
|
<p> TQSqlField represents the characteristics of a single column in a
|
||
|
|
database table or view, such as the data type and column name. A
|
||
|
|
field also contains the value of the database column, which can be
|
||
|
|
viewed or changed.
|
||
|
|
<p> Field data values are stored as TQVariants. Using an incompatible
|
||
|
|
type is not permitted. For example:
|
||
|
|
<p> <pre>
|
||
|
|
TQSqlField f( "myfield", TQVariant::Int );
|
||
|
|
f.<a href="#setValue">setValue</a>( TQPixmap() ); // will not work
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p> However, the field will attempt to cast certain data types to the
|
||
|
|
field data type where possible:
|
||
|
|
<p> <pre>
|
||
|
|
TQSqlField f( "myfield", TQVariant::Int );
|
||
|
|
f.<a href="#setValue">setValue</a>( TQString("123") ); // casts TQString to int
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p> TQSqlField objects are rarely created explicitly in application
|
||
|
|
code. They are usually accessed indirectly through <a href="qsqlrecord.html">TQSqlRecord</a>
|
||
|
|
or <a href="qsqlcursor.html">TQSqlCursor</a> which already contain a list of fields. For
|
||
|
|
example:
|
||
|
|
<p> <pre>
|
||
|
|
<a href="qsqlcursor.html">TQSqlCursor</a> cur( "Employee" ); // create cursor using the 'Employee' table
|
||
|
|
TQSqlField* f = cur.<a href="qsqlrecord.html#field">field</a>( "name" ); // use the 'name' field
|
||
|
|
f-><a href="#setValue">setValue</a>( "Dave" ); // set field value
|
||
|
|
...
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p> In practice we rarely need to extract a pointer to a field at all.
|
||
|
|
The previous example would normally be written:
|
||
|
|
<p> <pre>
|
||
|
|
<a href="qsqlcursor.html">TQSqlCursor</a> cur( "Employee" );
|
||
|
|
cur.<a href="qsqlrecord.html#setValue">setValue</a>( "name", "Dave" );
|
||
|
|
...
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p>See also <a href="database.html">Database Classes</a>.
|
||
|
|
|
||
|
|
<hr><h2>Member Function Documentation</h2>
|
||
|
|
<h3 class=fn><a name="TQSqlField"></a>TQSqlField::TQSqlField ( const <a href="qstring.html">TQString</a> & fieldName = TQString::null, <a href="qvariant.html#Type-enum">TQVariant::Type</a> type = TQVariant::Invalid )
|
||
|
|
</h3>
|
||
|
|
Constructs an empty field called <em>fieldName</em> of type <em>type</em>.
|
||
|
|
|
||
|
|
<h3 class=fn><a name="TQSqlField-2"></a>TQSqlField::TQSqlField ( const <a href="qsqlfield.html">TQSqlField</a> & other )
|
||
|
|
</h3>
|
||
|
|
Constructs a copy of <em>other</em>.
|
||
|
|
|
||
|
|
<h3 class=fn><a name="~TQSqlField"></a>TQSqlField::~TQSqlField ()<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
Destroys the object and frees any allocated resources.
|
||
|
|
|
||
|
|
<h3 class=fn>void <a name="clear"></a>TQSqlField::clear ( bool nullify = TRUE )
|
||
|
|
</h3>
|
||
|
|
Clears the value of the field. If the field is read-only, nothing
|
||
|
|
happens. If <em>nullify</em> is TRUE (the default), the field is set to
|
||
|
|
NULL.
|
||
|
|
|
||
|
|
<h3 class=fn>bool <a name="isNull"></a>TQSqlField::isNull () const
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Returns TRUE if the field is currently NULL; otherwise returns
|
||
|
|
FALSE.
|
||
|
|
|
||
|
|
<h3 class=fn>bool <a name="isReadOnly"></a>TQSqlField::isReadOnly () const
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Returns TRUE if the field's value is read only; otherwise returns
|
||
|
|
FALSE.
|
||
|
|
|
||
|
|
<h3 class=fn><a href="qstring.html">TQString</a> <a name="name"></a>TQSqlField::name () const
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Returns the name of the field.
|
||
|
|
|
||
|
|
<p>Example: <a href="sql.html#x2249">sql/overview/table4/main.cpp</a>.
|
||
|
|
<h3 class=fn><a href="qsqlfield.html">TQSqlField</a> & <a name="operator-eq"></a>TQSqlField::operator= ( const <a href="qsqlfield.html">TQSqlField</a> & other )
|
||
|
|
</h3>
|
||
|
|
Sets the field equal to <em>other</em>.
|
||
|
|
|
||
|
|
<h3 class=fn>bool <a name="operator-eq-eq"></a>TQSqlField::operator== ( const <a href="qsqlfield.html">TQSqlField</a> & other ) const
|
||
|
|
</h3>
|
||
|
|
Returns TRUE if the field is equal to <em>other</em>; otherwise returns
|
||
|
|
FALSE. Fields are considered equal when the following field
|
||
|
|
properties are the same:
|
||
|
|
<p> <ul>
|
||
|
|
<li> <a href="#name">name</a>()
|
||
|
|
<li> <a href="#isNull">isNull</a>()
|
||
|
|
<li> <a href="#value">value</a>()
|
||
|
|
<li> <a href="#isReadOnly">isReadOnly</a>()
|
||
|
|
</ul>
|
||
|
|
<p>
|
||
|
|
<h3 class=fn>void <a name="setName"></a>TQSqlField::setName ( const <a href="qstring.html">TQString</a> & name )<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Sets the name of the field to <em>name</em>.
|
||
|
|
|
||
|
|
<h3 class=fn>void <a name="setNull"></a>TQSqlField::setNull ()<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Sets the field to NULL and clears the value using <a href="#clear">clear</a>(). If the
|
||
|
|
field is read-only, nothing happens.
|
||
|
|
<p> <p>See also <a href="#isReadOnly">isReadOnly</a>() and <a href="#clear">clear</a>().
|
||
|
|
|
||
|
|
<h3 class=fn>void <a name="setReadOnly"></a>TQSqlField::setReadOnly ( bool readOnly )<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Sets the read only flag of the field's value to <em>readOnly</em>.
|
||
|
|
<p> <p>See also <a href="#setValue">setValue</a>().
|
||
|
|
|
||
|
|
<h3 class=fn>void <a name="setValue"></a>TQSqlField::setValue ( const <a href="qvariant.html">TQVariant</a> & value )<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
Sets the value of the field to <em>value</em>. If the field is read-only
|
||
|
|
(<a href="#isReadOnly">isReadOnly</a>() returns TRUE), nothing happens. If the data type of
|
||
|
|
<em>value</em> differs from the field's current data type, an attempt is
|
||
|
|
made to cast it to the proper type. This preserves the data type
|
||
|
|
of the field in the case of assignment, e.g. a <a href="qstring.html">TQString</a> to an
|
||
|
|
integer data type. For example:
|
||
|
|
<p> <pre>
|
||
|
|
<a href="qsqlcursor.html">TQSqlCursor</a> cur( "Employee" ); // 'Employee' table
|
||
|
|
TQSqlField* f = cur.<a href="qsqlrecord.html#field">field</a>( "student_count" ); // an integer field
|
||
|
|
...
|
||
|
|
f-><a href="#setValue">setValue</a>( myLineEdit->text() ); // cast the line edit text to an integer
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<p> <p>See also <a href="#isReadOnly">isReadOnly</a>().
|
||
|
|
|
||
|
|
<h3 class=fn><a href="qvariant.html#Type-enum">TQVariant::Type</a> <a name="type"></a>TQSqlField::type () const
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Returns the field's type as stored in the database.
|
||
|
|
Note that the actual value might have a different type,
|
||
|
|
Numerical values that are too large to store in a long
|
||
|
|
int or double are usually stored as strings to prevent
|
||
|
|
precision loss.
|
||
|
|
|
||
|
|
<h3 class=fn><a href="qvariant.html">TQVariant</a> <a name="value"></a>TQSqlField::value () const<tt> [virtual]</tt>
|
||
|
|
</h3>
|
||
|
|
|
||
|
|
<p> Returns the value of the field as a <a href="qvariant.html">TQVariant</a>.
|
||
|
|
|
||
|
|
<p>Example: <a href="sql.html#x2250">sql/overview/table4/main.cpp</a>.
|
||
|
|
<!-- eof -->
|
||
|
|
<hr><p>
|
||
|
|
This file is part of the <a href="index.html">TQt 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>TQt 3.3.8</div>
|
||
|
|
</table></div></address></body>
|
||
|
|
</html>
|