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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- /home/reggie/tmp/qt-3.0-reggie-5401/qt-x11-commercial-3.0.5/src/sql/qsqlfield.cpp:287 --><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>QSqlFieldInfo Class</title><style type="text/css"><!--h3.fn,span.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>QSqlFieldInfo Class Reference<br><small>[<a href="sql.html">sql module</a>]</small></h1><p>The QSqlFieldInfo class stores meta data associated with a SQL field.<a href="#details">More...</a><p><tt>#include <<a href="qsqlfield-h.html">qsqlfield.h</a>></tt><p><a href="qsqlfieldinfo-members.html">List of all member functions.</a><h2>Public Members</h2><ul><li><div class=fn><a href="#QSqlFieldInfo"><b>QSqlFieldInfo</b></a> ( const QString & name = QString::null, QVariant::Type typ = QVariant::Invalid, int required = -1, int len = -1, int prec = -1, const QVariant & defValue = QVariant ( ), int typeID = 0, bool generated = TRUE, bool trim = FALSE, bool calculated = FALSE )</div></li><li><div class=fn><a href="#QSqlFieldInfo-2"><b>QSqlFieldInfo</b></a> ( const QSqlFieldInfo & other )</div></li><li><div class=fn><a href="#QSqlFieldInfo-3"><b>QSqlFieldInfo</b></a> ( const QSqlField & other, bool generated = TRUE )</div></li><li><div class=fn>virtual <a href="#~QSqlFieldInfo"><b>~QSqlFieldInfo</b></a> ()</div></li><li><div class=fn>QSqlFieldInfo & <a href="#operator-eq"><b>operator=</b></a> ( const QSqlFieldInfo & other )</div></li><li><div class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const QSqlFieldInfo & f ) const</div></li><li><div class=fn>QSqlField <a href="#toField"><b>toField</b></a> () const</div></li><li><div class=fn>int <a href="#isRequired"><b>isRequired</b></a> () const</div></li><li><div class=fn>QVariant::Type <a href="#type"><b>type</b></a> () const</div></li><li><div class=fn>int <a href="#length"><b>length</b></a> () const</div></li><li><div class=fn>int <a href="#precision"><b>precision</b></a> () const</div></li><li><div class=fn>QVariant <a href="#defaultValue"><b>defaultValue</b></a> () const</div></li><li><div class=fn>QString <a href="#name"><b>name</b></a> () const</div></li><li><div class=fn>int <a href="#typeID"><b>typeID</b></a> () const</div></li><li><div class=fn>bool <a href="#isGenerated"><b>isGenerated</b></a> () const</div></li><li><div class=fn>bool <a href="#isTrim"><b>isTrim</b></a> () const</div></li><li><div class=fn>bool <a href="#isCalculated"><b>isCalculated</b></a> () const</div></li><li><div class=fn>virtual void <a href="#setTrim"><b>setTrim</b></a> ( bool trim )</div></li><li><div class=fn>virtual void <a href="#setGenerated"><b>setGenerated</b></a> ( bool gen )</div></li><li><div class=fn>virtual void <a href="#setCalculated"><b>setCalculated</b></a> ( bool calc )</div></li></ul><hr><a name="details"></a><h2>Detailed Description</h2>The QSqlFieldInfo class stores meta data associated with a SQL field.<p> QSqlFieldInfo objects only store meta data; field values arestored in <a href="qsqlfield.html">QSqlField</a> objects.<p> All values must be set in the constructor, and may be retrievedusing <a href="#isRequired">isRequired</a>(), <a href="#type">type</a>(), <a href="#length">length</a>(), <a href="#precision">precision</a>(), <a href="#defaultValue">defaultValue</a>(),<a href="#name">name</a>(), <a href="#isGenerated">isGenerated</a>() and <a href="#typeID">typeID</a>().<p>See also <a href="database.html">Database Classes</a>.<hr><h2>Member Function Documentation</h2><h3 class=fn><a name="QSqlFieldInfo"></a>QSqlFieldInfo::QSqlFieldInfo ( const <a href="qstring.html">QString</a> & name = QString::null, <a href="qvariant.html#Type-enum">QVariant::Type</a> typ = QVariant::Invalid, int required = -1, int len = -1, int prec = -1, const <a href="qvariant.html">QVariant</a> & defValue = QVariant ( ), int typeID = 0, bool generated = TRUE, bool trim = FALSE, bool calculated = FALSE )</h3>Constructs a QSqlFieldInfo with the following parameters:<ul><li> <em>name</em> the name of the field.<li> <em>typ</em> the field's type in a <a href="qvariant.html">QVariant</a>.<li> <em>required</em> greater than 0 if the field is required, 0 if its value canbe NULL and less than 0 if it cannot be determined whether the fieldis required or not.<li> <em>len</em> the length of the field. Note that for non-charactertypes some databases return either the length in bytes or the numberof digits. -1 signifies that the length cannot be determined.<li> <em>prec</em> the precision of the field, or -1 if the field has noprecision or it cannot be determined.<li> <em>defValue</em> the default value that is inserted into the table ifnone is specified by the user. QVariant() if there is no defaultvalue or it cannot be determined.<li> <em>typeID</em> the internal typeID of the database system (onlyuseful for low-level programming). 0 if unknown.<li> <em>generated</em> TRUE indicates that this field should be includedin auto-generated SQL statments, e.g. in <a href="qsqlcursor.html">QSqlCursor</a>.<li> <em>trim</em> TRUE indicates that widgets should remove trailingwhitespace from character fields. This does not affect the fieldvalue but only its representation inside widgets.<li> <em>calculated</em> TRUE indicates that the value of this field iscalculated. The value of calculated fields can by modified by subclassing QSqlCursor and overriding <a href="qsqlcursor.html#calculateField">QSqlCursor::calculateField</a>().</ul><h3 class=fn><a name="QSqlFieldInfo-2"></a>QSqlFieldInfo::QSqlFieldInfo ( const <a href="qsqlfieldinfo.html">QSqlFieldInfo</a> & other )</h3> Constructs a copy of <em>other</em>.<h3 class=fn><a name="QSqlFieldInfo-3"></a>QSqlFieldInfo::QSqlFieldInfo ( const <a href="qsqlfield.html">QSqlField</a> & other, bool generated = TRUE )</h3>Creates a QSqlFieldInfo object with the type and the name of the<a href="qsqlfield.html">QSqlField</a> <em>other</em>. If <em>generated</em> is TRUE this field will be includedin auto-generated SQL statments, e.g. in <a href="qsqlcursor.html">QSqlCursor</a>.<h3 class=fn><a name="~QSqlFieldInfo"></a>QSqlFieldInfo::~QSqlFieldInfo ()<tt> [virtual]</tt></h3>Destroys the object and frees any allocated resources.<h3 class=fn><a href="qvariant.html">QVariant</a> <a name="defaultValue"></a>QSqlFieldInfo::defaultValue () const</h3>Returns the default value of this field or an empty <a href="qvariant.html">QVariant</a> ifthe field has no default value or the value couldn't bedetermined. The default value is the value inserted in thedatabase when it was not explicitly specified by the user.<h3 class=fn>bool <a name="isCalculated"></a>QSqlFieldInfo::isCalculated () const</h3>Returns TRUE if the field is calculated.<p> <p>See also <a href="#setCalculated">setCalculated</a>().<h3 class=fn>bool <a name="isGenerated"></a>QSqlFieldInfo::isGenerated () const</h3>Returns TRUE if this field should be included in auto-generatedSQL statments, e.g. in <a href="qsqlcursor.html">QSqlCursor</a>; otherwise returns FALSE.<p> <p>See also <a href="#setGenerated">setGenerated</a>().<h3 class=fn>int <a name="isRequired"></a>QSqlFieldInfo::isRequired () const</h3>Returns a value greater than 0 if the field is required (NULLvalues are not allowed), 0 if it isn't required (NULL values areallowed) or less than 0 if it cannot be determined whether thefield is required or not.<h3 class=fn>bool <a name="isTrim"></a>QSqlFieldInfo::isTrim () const</h3>Returns TRUE if trailing whitespace should be removed from characterfields.<p> <p>See also <a href="#setTrim">setTrim</a>().<h3 class=fn>int <a name="length"></a>QSqlFieldInfo::length () const</h3>Returns the length of this field. For fields storing text thereturn value is the maximum number of characters the field canhold. For non-character fields some database systems return thenumber of bytes needed or the number of digits allowed. If thelength cannot be determined -1 is returned.<h3 class=fn><a href="qstring.html">QString</a> <a name="name"></a>QSqlFieldInfo::name () const</h3> Returns the name of the field in the SQL table.<p>Examples: <a href="sql.html#x2259">sql/overview/subclass3/main.cpp</a> and <a href="sql.html#x2263">sql/overview/subclass4/main.cpp</a>.<h3 class=fn><a href="qsqlfieldinfo.html">QSqlFieldInfo</a> & <a name="operator-eq"></a>QSqlFieldInfo::operator= ( const <a href="qsqlfieldinfo.html">QSqlFieldInfo</a> & other )</h3> Assigns <em>other</em> to this field info and returns a reference to it.<h3 class=fn>bool <a name="operator-eq-eq"></a>QSqlFieldInfo::operator== ( const <a href="qsqlfieldinfo.html">QSqlFieldInfo</a> & f ) const</h3> Returns TRUE if this fieldinfo is equal to <em>f</em>; otherwise returns FALSE.<p> Two field infos are considered equal when all their attributes match.<h3 class=fn>int <a name="precision"></a>QSqlFieldInfo::precision () const</h3> Returns the precision of this field or -1 if the field has no precisionor it cannot be determined.<h3 class=fn>void <a name="setCalculated"></a>QSqlFieldInfo::setCalculated ( bool calc )<tt> [virtual]</tt></h3><em>calc</em> set to TRUE indicates that this field is a calculatedfield. The value of calculated fields can by modified by subclassing<a href="qsqlcursor.html">QSqlCursor</a> and overriding <a href="qsqlcursor.html#calculateField">QSqlCursor::calculateField</a>().<p> <p>See also <a href="#isCalculated">isCalculated</a>().<h3 class=fn>void <a name="setGenerated"></a>QSqlFieldInfo::setGenerated ( bool gen )<tt> [virtual]</tt></h3><em>gen</em> set to FALSE indicates that this field should not appear in auto-generated SQL statements (for example in <a href="qsqlcursor.html">QSqlCursor</a>).<p> <p>See also <a href="#isGenerated">isGenerated</a>().<h3 class=fn>void <a name="setTrim"></a>QSqlFieldInfo::setTrim ( bool trim )<tt> [virtual]</tt></h3>If <em>trim</em> is TRUE widgets should remove trailingwhitespace from character fields. This does not affect the fieldvalue but only its representation inside widgets. <p> <p>See also <a href="#isTrim">isTrim</a>().<h3 class=fn><a href="qsqlfield.html">QSqlField</a> <a name="toField"></a>QSqlFieldInfo::toField () const</h3>Returns an empty <a href="qsqlfield.html">QSqlField</a> based on the informationin this QSqlFieldInfo.<h3 class=fn><a href="qvariant.html#Type-enum">QVariant::Type</a> <a name="type"></a>QSqlFieldInfo::type () const</h3> Returns the type of this field or QVariant::Invalid if the type is unknown.<h3 class=fn>int <a name="typeID"></a>QSqlFieldInfo::typeID () const</h3>Returns the internal type identifier as returned from the database system.The return value is 0 if the type is unknown.<p> <b>Warning:</b> This information is only useful for low-level databaseprogramming and is <em>not</em> database independent.<!-- eof --><hr><p>This file is part of the <a href="index.html">Qt toolkit</a>.Copyright © 1995-2002<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 © 2002 <a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a><td align=right><div align=right>Qt version 3.0.5</div></table></div></address></body></html>⌨️ 快捷键说明
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