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2010-05-25T14:21:06Z

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==Connect to Sqlite and do insert, delete, update and select==

<source lang="cpp">
Foundations of Qt Development\Chapter13\sqltest\sqlite\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( "./testdatabase.db" );
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!" );
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;
}

</source>

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в 14:21, 25 мая 2010

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