C++/Qt/QSqlDatabase

Содержание

1 Connect to MySql with QSqlDatabase, and do select, update, insert and delete
2 Operate Sqlite database with QSqlDatabase
3 Prepared statement
4 Set up QSqlDatabase
5 Using sql database from Qt

Connect to MySql with QSqlDatabase, and do select, update, insert and delete

  

Foundations of Qt Development\Chapter13\sqltest\mysql\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QtSql>
#include <QtDebug>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QSqlDatabase db = QSqlDatabase::addDatabase( "QMYSQL" );
  db.setHostName( "localhost" );
  db.setDatabaseName( "qtbook" );
  db.setUserName( "root" );
  db.setPassword( "sa" );
  if( !db.open() )
  {
    qDebug() << db.lastError();
    qFatal( "Failed to connect." );
  }
    
  qDebug( "Connected!" );
  
  QSqlQuery qry;
  qry.prepare( "CREATE TABLE IF NOT EXISTS names (id INTEGER UNIQUE PRIMARY KEY, firstname VARCHAR(30), lastname VARCHAR(30))" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug() << "Table created!";
    
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (1, "John", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (2, "Jane", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (3, "James", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (4, "Judy", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (5, "Richard", "Roe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (6, "Jane", "Roe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (7, "John", "Noakes")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (8, "Donna", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (9, "Ralph", "Roe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
// SALARIES
  qry.prepare( "CREATE TABLE IF NOT EXISTS salaries (id INTEGER UNIQUE PRIMARY KEY, annual INTEGER)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (1, 1000)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (2, 900)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (3, 900)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (5, 1100)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (6, 1000)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (8, 1200)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (9, 1200)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "SELECT * FROM salaries" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.firstname, names.lastname, salaries.annual FROM names JOIN salaries ON names.id = salaries.id" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.firstname, names.lastname, salaries.annual FROM names LEFT JOIN salaries ON names.id = salaries.id" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.lastname, SUM(salaries.annual)/COUNT(*) AS "Average", MIN(salaries.annual) AS "Minimum", MAX(salaries.annual) AS "Maximum" FROM names LEFT JOIN salaries ON names.id = salaries.id GROUP BY names.lastname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
// SALARIES
  qry.prepare( "SELECT * FROM names" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }
  
  
  qry.prepare( "SELECT firstname, lastname FROM names WHERE lastname = "Roe"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }

  qry.prepare( "SELECT firstname, lastname FROM names WHERE lastname = "Roe" ORDER BY firstname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }

  qry.prepare( "SELECT lastname, COUNT(*) as "members" FROM names GROUP BY lastname ORDER BY lastname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }
  
  qry.prepare( "UPDATE names SET firstname = "Nisse", lastname = "Svensson" WHERE id = 7" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Updated!" );
  qry.prepare( "UPDATE names SET lastname = "Johnson" WHERE firstname = "Jane"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Updated!" );
  
  qry.prepare( "DELETE FROM names WHERE id = 7" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Deleted!" );
  qry.prepare( "DELETE FROM names WHERE lastname = "Johnson"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Deleted!" );
    
  db.close();
  return 0;
}

Operate Sqlite database with QSqlDatabase

  
Foundations of Qt Development\Chapter13\modelview\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QTableView>
#include <QtSql>
void relModel()
{
  QSqlRelationalTableModel *model = new QSqlRelationalTableModel();
  
  model->setTable( "names" );
  model->setRelation( 0, QSqlRelation( "salaries", "id", "annual" ) );
  model->select();
  
  model->setHeaderData( 0, Qt::Horizontal, QObject::tr("Annual Pay") );
  model->setHeaderData( 1, Qt::Horizontal, QObject::tr("First Name") );
  model->setHeaderData( 2, Qt::Horizontal, QObject::tr("Last Name") );
    
  QTableView *view = new QTableView();
  view->setModel( model );
  view->show();
}
void tabModel()
{
  QSqlTableModel *model = new QSqlTableModel();
  
  model->setTable( "names" );
  model->setFilter( "lastname = "Doe"" );
  model->select();
  
  model->removeColumn( 0 );
    
  QTableView *view = new QTableView();
  view->setModel( model );
  view->show();
}
void qryModel()
{
  QSqlQueryModel *model = new QSqlQueryModel();
  model->setQuery( "SELECT firstname, lastname FROM names" );
    
  QTableView *view = new QTableView();
  view->setModel( model );
  view->show();
}

int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
  db.setDatabaseName( ":memory:" );
  
  if( !db.open() )
  {
    qDebug() << db.lastError();
    qFatal( "Failed to connect." );
  }
    
  qDebug( "Connected!" );
  
  QSqlQuery qry;
  qry.prepare( "CREATE TABLE IF NOT EXISTS names (id INTEGER UNIQUE PRIMARY KEY, firstname VARCHAR(30), lastname VARCHAR(30))" );
  qry.exec();
    
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (1, "John", "Doe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (2, "Jane", "Doe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (3, "James", "Doe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (4, "Judy", "Doe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (5, "Richard", "Roe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (6, "Jane", "Roe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (7, "John", "Noakes")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (8, "Donna", "Doe")" );
  qry.exec();
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (:id, :firstname, :lastname)" );
  qry.bindValue( ":id", 9 );
  qry.bindValue( ":firstname", "Ralph" );
  qry.bindValue( ":lastname", "Roe" );
  qry.exec();
  qry.prepare( "CREATE TABLE IF NOT EXISTS salaries (id INTEGER UNIQUE PRIMARY KEY, annual INTEGER)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (1, 1000)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (2, 900)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (3, 900)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (5, 1100)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (6, 1000)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (8, 1200)" );
  qry.exec();
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (9, 1200)" );
  qry.exec();
  relModel();
  tabModel();
  qryModel();
  
  return app.exec();
}

Prepared statement

  

Foundations of Qt Development\Chapter13\sqltest\sqlite-mem\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QtSql>
#include <QtDebug>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QSqlDatabase db = QSqlDatabase::addDatabase( "QSQLITE" );
  db.setDatabaseName( ":memory:" );
  
  if( !db.open() )
  {
    qDebug() << db.lastError();
    qFatal( "Failed to connect." );
  }
    
  qDebug( "Connected!" );
  
  QSqlQuery qry;
  qry.prepare( "CREATE TABLE IF NOT EXISTS names (id INTEGER UNIQUE PRIMARY KEY, firstname VARCHAR(30), lastname VARCHAR(30))" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug() << "Table created!";
    
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (1, "John", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (2, "Jane", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (3, "James", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (4, "Judy", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (5, "Richard", "Roe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (6, "Jane", "Roe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (7, "John", "Noakes")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (8, "Donna", "Doe")" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO names (id, firstname, lastname) VALUES (:id, :firstname, :lastname)" );
  qry.bindValue( ":id", 9 );
  qry.bindValue( ":firstname", "Ralph" );
  qry.bindValue( ":lastname", "Roe" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
// SALARIES
  qry.prepare( "CREATE TABLE IF NOT EXISTS salaries (id INTEGER UNIQUE PRIMARY KEY, annual INTEGER)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (1, 1000)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (2, 900)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (3, 900)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (5, 1100)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (6, 1000)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (8, 1200)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "INSERT INTO salaries (id, annual) VALUES (9, 1200)" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Inserted!" );
  qry.prepare( "SELECT * FROM salaries" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.firstname, names.lastname, salaries.annual FROM names JOIN salaries ON names.id = salaries.id" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.firstname, names.lastname, salaries.annual FROM names LEFT JOIN salaries ON names.id = salaries.id" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
  qry.prepare( "SELECT names.lastname, SUM(salaries.annual)/COUNT(*) AS "Average", MIN(salaries.annual) AS "Minimum", MAX(salaries.annual) AS "Maximum" FROM names LEFT JOIN salaries ON names.id = salaries.id GROUP BY names.lastname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }
// SALARIES

  qry.prepare( "SELECT * FROM names" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }
  
  
  qry.prepare( "SELECT firstname, lastname FROM names WHERE lastname = "Roe"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }

  qry.prepare( "SELECT firstname, lastname FROM names WHERE lastname = "Roe" ORDER BY firstname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    int cols = rec.count();
    
    QString temp;
    for( int c=0; c<cols; c++ )
      temp += rec.fieldName(c) + ((c<cols-1)?"\t":"");
    qDebug() << temp;
      
    while( qry.next() )
    {
      temp = "";
      for( int c=0; c<cols; c++ )
        temp += qry.value(c).toString() + ((c<cols-1)?"\t":"");
      qDebug() << temp;
    }
  }

  qry.prepare( "SELECT lastname, COUNT(*) as "members" FROM names GROUP BY lastname ORDER BY lastname" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
  {
    qDebug( "Selected!" );
    
    QSqlRecord rec = qry.record();
    
    int cols = rec.count();
    
    for( int c=0; c<cols; c++ )
      qDebug() << QString( "Column %1: %2" ).arg( c ).arg( rec.fieldName(c) );
      
    for( int r=0; qry.next(); r++ )
      for( int c=0; c<cols; c++ )
        qDebug() << QString( "Row %1, %2: %3" ).arg( r ).arg( rec.fieldName(c) ).arg( qry.value(c).toString() );
  }
  
  qry.prepare( "UPDATE names SET firstname = "Nisse", lastname = "Svensson" WHERE id = 7" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Updated!" );
  qry.prepare( "UPDATE names SET lastname = "Johnson" WHERE firstname = "Jane"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Updated!" );
  
  qry.prepare( "DELETE FROM names WHERE id = 7" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Deleted!" );
  qry.prepare( "DELETE FROM names WHERE lastname = "Johnson"" );
  if( !qry.exec() )
    qDebug() << qry.lastError();
  else
    qDebug( "Deleted!" );
  db.close();
  return 0;
}

Set up QSqlDatabase

  
#include <QtGui>
#include <QtSql>
#include <QDebug>
int main(int argc, char* argv[])
{
  QApplication app(argc, argv);
  QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
  db.setHostName("url.example.com");
  db.setDatabaseName("databaseName");
  db.setUserName("user");
  db.setPassword("pass");
  if (!db.open()) {
     qDebug() << db.lastError();
     return1;
  }

Using sql database from Qt

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
#include <QtSql>
#include <iostream>
using namespace std;
QString tr(const char *text)
{
    return QApplication::translate(text, text);
}
void QSqlDatabase_snippets()
{
    {
    QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
    db.setHostName("acidalia");
    db.setDatabaseName("customdb");
    db.setUserName("mojito");
    db.setPassword("J0a1m8");
    bool ok = db.open();
    Q_UNUSED(ok);
    }
    {
    QSqlDatabase db = QSqlDatabase::database();
    }
}
void QSqlField_snippets()
{
#if 0
    {
    QSqlField field("age", QVariant::Int);
    field.setValue(QPixmap());  // WRONG
    }
#endif
    {
    QSqlField field("age", QVariant::Int);
    field.setValue(QString("123"));  // casts QString to int
    }
    {
    QSqlQuery query;
 
    QSqlRecord record = query.record();
 
    QSqlField field = record.field("country");
    }
}
void doSomething(const QString &)
{
}
void QSqlQuery_snippets()
{
    {
    // typical loop
    QSqlQuery query("SELECT country FROM artist");
    while (query.next()) {
        QString country = query.value(0).toString();
        doSomething(country);
    }
    }
    {
    // field index lookup
    QSqlQuery query("SELECT * FROM artist");
    int fieldNo = query.record().indexOf("country");
    while (query.next()) {
        QString country = query.value(fieldNo).toString();
        doSomething(country);
    }
    }
    {
    // named with named
    QSqlQuery query;
    query.prepare("INSERT INTO person (id, forename, surname) "
                  "VALUES (:id, :forename, :surname)");
    query.bindValue(":id", 1001);
    query.bindValue(":forename", "Bart");
    query.bindValue(":surname", "Simpson");
    query.exec();
    }
    {
    // positional with named
    QSqlQuery query;
    query.prepare("INSERT INTO person (id, forename, surname) "
                  "VALUES (:id, :forename, :surname)");
    query.bindValue(0, 1001);
    query.bindValue(1, "Bart");
    query.bindValue(2, "Simpson");
    query.exec();
    }
    {
    // positional 1
    QSqlQuery query;
    query.prepare("INSERT INTO person (id, forename, surname) "
                  "VALUES (?, ?, ?)");
    query.bindValue(0, 1001);
    query.bindValue(1, "Bart");
    query.bindValue(2, "Simpson");
    query.exec();
    }
    {
    // positional 2
    QSqlQuery query;
    query.prepare("INSERT INTO person (id, forename, surname) "
                  "VALUES (?, ?, ?)");
    query.addBindValue(1001);
    query.addBindValue("Bart");
    query.addBindValue("Simpson");
    query.exec();
    }
    {
    // stored
    QSqlQuery query;
    query.prepare("CALL AsciiToInt(?, ?)");
    query.bindValue(0, "A");
    query.bindValue(1, 0, QSql::Out);
    query.exec();
    int i = query.boundValue(1).toInt(); // i is 65
    Q_UNUSED(i);
    }
    QSqlQuery query;
    {
    // examine with named binding
    QMapIterator<QString, QVariant> i(query.boundValues());
    while (i.hasNext()) {
        i.next();
        cout << i.key().toAscii().data() << ": "
             << i.value().toString().toAscii().data() << endl;
    }
    }
    {
    // examine with positional binding
    QList<QVariant> list = query.boundValues().values();
    for (int i = 0; i < list.size(); ++i)
        cout << i << ": " << list.at(i).toString().toAscii().data() << endl;
    }
}
void QSqlQueryModel_snippets()
{
    {
    QSqlQueryModel *model = new QSqlQueryModel;
    model->setQuery("SELECT name, salary FROM employee");
    model->setHeaderData(0, Qt::Horizontal, tr("Name"));
    model->setHeaderData(1, Qt::Horizontal, tr("Salary"));

    QTableView *view = new QTableView;
 
    view->setModel(model);
 
    view->show();
  
    view->setEditTriggers(QAbstractItemView::NoEditTriggers);
    }

    QSqlQueryModel model;
    model.setQuery("SELECT * FROM employee");
    int salary = model.record(4).value("salary").toInt();
    Q_UNUSED(salary);
    {
    int salary = model.data(model.index(4, 2)).toInt();
    Q_UNUSED(salary);
    }
    for (int row = 0; row < model.rowCount(); ++row) {
        for (int col = 0; col < model.columnCount(); ++col) {
            qDebug() << model.data(model.index(row, col));
        }
    }
}
class MyModel : public QSqlQueryModel
{
public:
    QVariant data(const QModelIndex &item, int role) const;
    int m_specialColumnNo;
};

QVariant MyModel::data(const QModelIndex &item, int role) const
{
    if (item.column() == m_specialColumnNo) {
        // handle column separately
    }
    return QSqlQueryModel::data(item, role);
}

void QSqlTableModel_snippets()
{
    QSqlTableModel *model = new QSqlTableModel;
    model->setTable("employee");
    model->setEditStrategy(QSqlTableModel::OnManualSubmit);
    model->select();
    model->removeColumn(0); // don"t show the ID
    model->setHeaderData(0, Qt::Horizontal, tr("Name"));
    model->setHeaderData(1, Qt::Horizontal, tr("Salary"));
    QTableView *view = new QTableView;
    view->setModel(model);
    view->show();

    {
    QSqlTableModel model;
    model.setTable("employee");
    QString name = model.record(4).value("name").toString();
    }
}
void sql_intro_snippets()
{
    {
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("bigblue");
    db.setDatabaseName("flightdb");
    db.setUserName("acarlson");
    db.setPassword("1uTbSbAs");
    bool ok = db.open();
    Q_UNUSED(ok);
    }
    {
    QSqlDatabase firstDB = QSqlDatabase::addDatabase("QMYSQL", "first");
    QSqlDatabase secondDB = QSqlDatabase::addDatabase("QMYSQL", "second");
    }
    {
    QSqlDatabase defaultDB = QSqlDatabase::database();
 
    QSqlDatabase firstDB = QSqlDatabase::database("first");
 
    QSqlDatabase secondDB = QSqlDatabase::database("second");
    }
    {
    // SELECT1
    QSqlQuery query;
    query.exec("SELECT name, salary FROM employee WHERE salary > 50000");

    while (query.next()) {
        QString name = query.value(0).toString();
        int salary = query.value(1).toInt();
        qDebug() << name << salary;
    }
    }
    {
    // FEATURE
    QSqlQuery query;
    int numRows;
    query.exec("SELECT name, salary FROM employee WHERE salary > 50000");
    QSqlDatabase defaultDB = QSqlDatabase::database();
    if (defaultDB.driver()->hasFeature(QSqlDriver::QuerySize)) {
        numRows = query.size();
    } else {
        // this can be very slow
        query.last();
        numRows = query.at() + 1;
    }
    }
    {
    // INSERT1
    QSqlQuery query;
    query.exec("INSERT INTO employee (id, name, salary) "
               "VALUES (1001, "Thad Beaumont", 65000)");
    }
    {
    // NAMED BINDING
    QSqlQuery query;
    query.prepare("INSERT INTO employee (id, name, salary) "
                  "VALUES (:id, :name, :salary)");
    query.bindValue(":id", 1001);
    query.bindValue(":name", "Thad Beaumont");
    query.bindValue(":salary", 65000);
    query.exec();
    }
    {
    // POSITIONAL BINDING
    QSqlQuery query;
    query.prepare("INSERT INTO employee (id, name, salary) "
                  "VALUES (?, ?, ?)");
    query.addBindValue(1001);
    query.addBindValue("Thad Beaumont");
    query.addBindValue(65000);
    query.exec();
    }
    {
    // UPDATE1
    QSqlQuery query;
    query.exec("UPDATE employee SET salary = 70000 WHERE id = 1003");
    }
    {
    // DELETE1
    QSqlQuery query;
    query.exec("DELETE FROM employee WHERE id = 1007");
    }
    {
    // TRANSACTION
    QSqlDatabase::database().transaction();
    QSqlQuery query;
    query.exec("SELECT id FROM employee WHERE name = "Torild Halvorsen"");
    if (query.next()) {
        int employeeId = query.value(0).toInt();
        query.exec("INSERT INTO project (id, name, ownerid) "
                   "VALUES (201, "Manhattan Project", "
                   + QString::number(employeeId) + ")");
    }
    QSqlDatabase::database().commit();
    }
    {
    // SQLQUERYMODEL1
    QSqlQueryModel model;
    model.setQuery("SELECT * FROM employee");
    for (int i = 0; i < model.rowCount(); ++i) {
        int id = model.record(i).value("id").toInt();
        QString name = model.record(i).value("name").toString();
        qDebug() << id << name;
    }
    }
    {
    // SQLTABLEMODEL1
    QSqlTableModel model;
    model.setTable("employee");
    model.setFilter("salary > 50000");
    model.setSort(2, Qt::DescendingOrder);
    model.select();
    for (int i = 0; i < model.rowCount(); ++i) {
        QString name = model.record(i).value("name").toString();
        int salary = model.record(i).value("salary").toInt();
        qDebug() << name << salary;
    }
    }
    {
    // SQLTABLEMODEL2
    QSqlTableModel model;
    model.setTable("employee");

    for (int i = 0; i < model.rowCount(); ++i) {
        QSqlRecord record = model.record(i);
        double salary = record.value("salary").toInt();
        salary *= 1.1;
        record.setValue("salary", salary);
        model.setRecord(i, record);
    }
    model.submitAll();

    // SQLTABLEMODEL3
    int row = 1;
    int column = 2;
    model.setData(model.index(row, column), 75000);
    model.submitAll();

    // SQLTABLEMODEL4
    model.insertRows(row, 1);
    model.setData(model.index(row, 0), 1013);
    model.setData(model.index(row, 1), "Peter Gordon");
    model.setData(model.index(row, 2), 68500);
    model.submitAll();

    model.removeRows(row, 5);
 
    model.submitAll();
    }
}

class XyzResult : public QSqlResult
{
public:
    XyzResult(const QSqlDriver *driver)
        : QSqlResult(driver) {}
    ~XyzResult() {}
protected:
    QVariant data(int /* index */) { return QVariant(); }
    bool isNull(int /* index */) { return false; }
    bool reset(const QString & /* query */) { return false; }
    bool fetch(int /* index */) { return false; }
    bool fetchFirst() { return false; }
    bool fetchLast() { return false; }
    int size() { return 0; }
    int numRowsAffected() { return 0; }
    QSqlRecord record() const { return QSqlRecord(); }
};

class XyzDriver : public QSqlDriver
{
public:
    XyzDriver() {}
    ~XyzDriver() {}
    bool hasFeature(DriverFeature /* feature */) const { return false; }
    bool open(const QString & /* db */, const QString & /* user */,
              const QString & /* password */, const QString & /* host */,
              int /* port */, const QString & /* options */)
        { return false; }
    void close() {}
    QSqlResult *createResult() const { return new XyzResult(this); }
};

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QSqlDatabase_snippets();
    QSqlField_snippets();
    QSqlQuery_snippets();
    QSqlQueryModel_snippets();
    QSqlTableModel_snippets();
    XyzDriver driver;
    XyzResult result(&driver);
}

C++/Qt/QSqlDatabase

Содержание

Connect to MySql with QSqlDatabase, and do select, update, insert and delete

Operate Sqlite database with QSqlDatabase

Prepared statement

Set up QSqlDatabase

Using sql database from Qt

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