Viadeo Twitter Google Bookmarks ! Facebook Digg del.icio.us MySpace Yahoo MyWeb Blinklist Netvouz Reddit Simpy StumbleUpon Bookmarks Windows Live Favorites 
Logo Documentation Qt ·  Page d'accueil  ·  Toutes les classes  ·  Classes principales  ·  Annotées  ·  Classes groupées  ·  Modules  ·  Fonctions  · 

QSqlResult Class Reference
[QtSql module]

The QSqlResult class provides an abstract interface for accessing data from specific SQL databases. More...

#include <QSqlResult>

Public Functions

Protected Types

Protected Functions


Detailed Description

The QSqlResult class provides an abstract interface for accessing data from specific SQL databases.

Normally, you would use QSqlQuery instead of QSqlResult, since QSqlQuery provides a generic wrapper for database-specific implementations of QSqlResult.

If you are implementing your own SQL driver (by subclassing QSqlDriver), you will need to provide your own QSqlResult subclass that implements all the pure virtual functions and other virtual functions that you need.

See also QSqlDriver.


Member Type Documentation

enum QSqlResult::BindingSyntax

This enum type specifies the different syntaxes for specifying placeholders in prepared queries.

ConstantValueDescription
QSqlResult::PositionalBinding0Use the ODBC-style positional syntax, with "?" as placeholders.
QSqlResult::NamedBinding1Use the Oracle-style syntax with named placeholders (e.g., ":id")

See also bindingSyntax().


Member Function Documentation

QSqlResult::QSqlResult ( const QSqlDriver * db )   [protected]

Creates a QSqlResult using database driver db. The object is initialized to an inactive state.

See also isActive() and driver().

QSqlResult::~QSqlResult ()   [virtual]

Destroys the object and frees any allocated resources.

void QSqlResult::addBindValue ( const QVariant & val, QSql::ParamType paramType )   [protected]

Binds the value val of parameter type paramType to the next available position in the current record (row).

See also bindValue().

int QSqlResult::at () const   [protected]

Returns the current (zero-based) row position of the result. May return the special values QSql::BeforeFirstRow or QSql::AfterLastRow.

See also setAt() and isValid().

void QSqlResult::bindValue ( int index, const QVariant & val, QSql::ParamType paramType )   [virtual protected]

Binds the value val of parameter type paramType to position index in the current record (row).

See also addBindValue().

void QSqlResult::bindValue ( const QString & placeholder, const QVariant & val, QSql::ParamType paramType )   [virtual protected]

This is an overloaded member function, provided for convenience.

Binds the value val of parameter type paramType to the placeholder name in the current record (row).

Note that binding an undefined placeholder will result in undefined behavior.

QSql::ParamType QSqlResult::bindValueType ( int index ) const   [protected]

Returns the parameter type for the value bound at position index.

See also boundValue().

QSql::ParamType QSqlResult::bindValueType ( const QString & placeholder ) const   [protected]

This is an overloaded member function, provided for convenience.

Returns the parameter type for the value bound with the given placeholder name.

BindingSyntax QSqlResult::bindingSyntax () const   [protected]

Returns the binding syntax used by prepared queries.

QVariant QSqlResult::boundValue ( int index ) const   [protected]

Returns the value bound at position index in the current record (row).

See also bindValue() and boundValues().

QVariant QSqlResult::boundValue ( const QString & placeholder ) const   [protected]

This is an overloaded member function, provided for convenience.

Returns the value bound by the given placeholder name in the current record (row).

See also bindValueType().

int QSqlResult::boundValueCount () const   [protected]

Returns the number of bound values in the result.

See also boundValues().

QString QSqlResult::boundValueName ( int index ) const   [protected]

Returns the name of the bound value at position index in the current record (row).

See also boundValue().

QVector<QVariant> & QSqlResult::boundValues () const   [protected]

Returns a vector of the result's bound values for the current record (row).

See also boundValueCount().

void QSqlResult::clear ()   [protected]

Clears the entire result set and releases any associated resources.

QVariant QSqlResult::data ( int index )   [pure virtual protected]

Returns the data for field index in the current row as a QVariant. This function is only called if the result is in an active state and is positioned on a valid record and index is non-negative. Derived classes must reimplement this function and return the value of field index, or QVariant() if it cannot be determined.

const QSqlDriver * QSqlResult::driver () const   [protected]

Returns the driver associated with the result. This is the object that was passed to the constructor.

bool QSqlResult::exec ()   [virtual protected]

Executes the query.

See also prepare().

QString QSqlResult::executedQuery () const   [protected]

Returns the query that was actually executed. This may differ from the query that was passed, for example if bound values were used with a prepared query and the underlying database doesn't support prepared queries.

See also exec() and setQuery().

bool QSqlResult::fetch ( int index )   [pure virtual protected]

Positions the result to an arbitrary (zero-based) row index.

This function is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the row index, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also isActive(), fetchFirst(), fetchLast(), fetchNext(), and fetchPrevious().

bool QSqlResult::fetchFirst ()   [pure virtual protected]

Positions the result to the first record (row 0) in the result.

This function is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the first record, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also fetch() and fetchLast().

bool QSqlResult::fetchLast ()   [pure virtual protected]

Positions the result to the last record (last row) in the result.

This function is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the last record, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also fetch() and fetchFirst().

bool QSqlResult::fetchNext ()   [virtual protected]

Positions the result to the next available record (row) in the result.

This function is only called if the result is in an active state. The default implementation calls fetch() with the next index. Derived classes can reimplement this function and position the result to the next record in some other way, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also fetch() and fetchPrevious().

bool QSqlResult::fetchPrevious ()   [virtual protected]

Positions the result to the previous record (row) in the result.

This function is only called if the result is in an active state. The default implementation calls fetch() with the previous index. Derived classes can reimplement this function and position the result to the next record in some other way, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

QVariant QSqlResult::handle () const   [virtual]

Returns the low-level database handle for this result set wrapped in a QVariant or an invalid QVariant if there is no handle.

Warning: Use this with uttermost care and only if you know what you're doing.

Warning: The handle returned here can become a stale pointer if the result is modified (for example, if you clear it).

Warning: The handle can be NULL if the result was not executed yet.

The handle returned here is database-dependent, you should query the type name of the variant before accessing it.

This example retrieves the handle for a sqlite result:

    QSqlQuery query = ...
    QVariant v = query.result()->handle();
    if (v.isValid() && v.typeName() == "sqlite3_stmt*") {
        // v.data() returns a pointer to the handle
        sqlite3_stmt *handle = *static_cast<sqlite3_stmt **>(v.data());
        if (handle != 0) { // check that it is not NULL
            ...
        }
    }

This snippet returns the handle for PostgreSQL or MySQL:

    if (v.typeName() == "PGresult*") {
        PGresult *handle = *static_cast<PGresult **>(v.data());
        if (handle != 0) ...
    }

    if (v.typeName() == "MYSQL_STMT*") {
        MYSQL_STMT *handle = *static_cast<MYSQL_STMT **>(v.data());
        if (handle != 0) ...
    }

See also QSqlDriver::handle().

bool QSqlResult::hasOutValues () const   [protected]

Returns true if at least one of the query's bound values is a QSql::Out or a QSql::InOut; otherwise returns false.

See also bindValueType().

bool QSqlResult::isActive () const   [protected]

Returns true if the result has records to be retrieved; otherwise returns false.

bool QSqlResult::isForwardOnly () const   [protected]

Returns true if you can only scroll forward through the result set; otherwise returns false.

See also setForwardOnly().

bool QSqlResult::isNull ( int index )   [pure virtual protected]

Returns true if the field at position index in the current row is null; otherwise returns false.

bool QSqlResult::isSelect () const   [protected]

Returns true if the current result is from a SELECT statement; otherwise returns false.

See also setSelect().

bool QSqlResult::isValid () const   [protected]

Returns true if the result is positioned on a valid record (that is, the result is not positioned before the first or after the last record); otherwise returns false.

See also at().

QSqlError QSqlResult::lastError () const   [protected]

Returns the last error associated with the result.

See also setLastError().

QVariant QSqlResult::lastInsertId () const   [virtual protected]

Returns the object ID of the most recent inserted row if the database supports it. An invalid QVariant will be returned if the query did not insert any value or if the database does not report the id back. If more than one row was touched by the insert, the behavior is undefined.

See also QSqlDriver::hasFeature().

QString QSqlResult::lastQuery () const   [protected]

Returns the current SQL query text, or an empty string if there isn't one.

See also setQuery().

int QSqlResult::numRowsAffected ()   [pure virtual protected]

Returns the number of rows affected by the last query executed, or -1 if it cannot be determined or if the query is a SELECT statement.

See also size().

bool QSqlResult::prepare ( const QString & query )   [virtual protected]

Prepares the given query for execution; the query will normally use placeholders so that it can be executed repeatedly.

See also exec().

QSqlRecord QSqlResult::record () const   [virtual protected]

Returns the current record if the query is active; otherwise returns an empty QSqlRecord.

The default implementation always returns an empty QSqlRecord.

See also isActive().

bool QSqlResult::reset ( const QString & query )   [pure virtual protected]

Sets the result to use the SQL statement query for subsequent data retrieval.

Derived classes must reimplement this function and apply the query to the database. This function is only called after the result is set to an inactive state and is positioned before the first record of the new result. Derived classes should return true if the query was successful and ready to be used, or false otherwise.

See also setQuery().

bool QSqlResult::savePrepare ( const QString & query )   [virtual protected]

Prepares the given query, using the underlying database functionality where possible.

See also prepare().

void QSqlResult::setActive ( bool active )   [virtual protected]

This function is provided for derived classes to set the internal active state to active.

See also isActive().

void QSqlResult::setAt ( int index )   [virtual protected]

This function is provided for derived classes to set the internal (zero-based) row position to index.

See also at().

void QSqlResult::setForwardOnly ( bool forward )   [virtual protected]

Sets forward only mode to forward. If forward is true, only fetchNext() is allowed for navigating the results. Forward only mode needs much less memory since results do not have to be cached. By default, this feature is disabled.

See also isForwardOnly() and fetchNext().

void QSqlResult::setLastError ( const QSqlError & error )   [virtual protected]

This function is provided for derived classes to set the last error to error.

See also lastError().

void QSqlResult::setQuery ( const QString & query )   [virtual protected]

Sets the current query for the result to query. You must call reset() to execute the query on the database.

See also reset() and lastQuery().

void QSqlResult::setSelect ( bool select )   [virtual protected]

This function is provided for derived classes to indicate whether or not the current statement is a SQL SELECT statement. The select parameter should be true if the statement is a SELECT statement; otherwise it should be false.

See also isSelect().

int QSqlResult::size ()   [pure virtual protected]

Returns the size of the SELECT result, or -1 if it cannot be determined or if the query is not a SELECT statement.

See also numRowsAffected().

Publicité

Best Of

Actualités les plus lues

Semaine
Mois
Année
  1. « Quelque chose ne va vraiment pas avec les développeurs "modernes" », un développeur à "l'ancienne" critique la multiplication des bibliothèques 94
  2. Apercevoir la troisième dimension ou l'utilisation multithreadée d'OpenGL dans Qt, un article des Qt Quarterly traduit par Guillaume Belz 0
  3. Pourquoi les programmeurs sont-ils moins payés que les gestionnaires de programmes ? Manquent-ils de pouvoir de négociation ? 43
  4. Les développeurs ignorent-ils trop les failles découvertes dans leur code ? Prenez-vous en compte les remarques des autres ? 17
  5. Quelles nouveautés de C++11 Visual C++ doit-il rapidement intégrer ? Donnez-nous votre avis 10
  6. Qt Commercial : Digia organise un webinar gratuit le 27 mars sur la conception d'interfaces utilisateur et d'applications avec le framework 0
  7. 2017 : un quinquennat pour une nouvelle version du C++ ? Possible, selon Herb Sutter 9
Page suivante

Le Qt Developer Network au hasard

Logo

QSqlTableModel en action

Le Qt Developer Network est un réseau de développeurs Qt anglophone, où ils peuvent partager leur expérience sur le framework. Lire l'article.

Communauté

Ressources

Liens utiles

Contact

  • Vous souhaitez rejoindre la rédaction ou proposer un tutoriel, une traduction, une question... ? Postez dans le forum Contribuez ou contactez-nous par MP ou par email (voir en bas de page).

Qt dans le magazine

Cette page est une traduction d'une page de la documentation de Qt, écrite par Nokia Corporation and/or its subsidiary(-ies). Les éventuels problèmes résultant d'une mauvaise traduction ne sont pas imputables à Nokia. Qt 4.1
Copyright © 2012 Developpez LLC. Tous droits réservés Developpez LLC. Aucune reproduction, même partielle, ne peut être faite de ce site et de l'ensemble de son contenu : textes, documents et images sans l'autorisation expresse de Developpez LLC. Sinon, vous encourez selon la loi jusqu'à 3 ans de prison et jusqu'à 300 000 E de dommages et intérêts. Cette page est déposée à la SACD.
Vous avez déniché une erreur ? Un bug ? Une redirection cassée ? Ou tout autre problème, quel qu'il soit ? Ou bien vous désirez participer à ce projet de traduction ? N'hésitez pas à nous contacter ou par MP !
 
 
 
 
Partenaires

Hébergement Web