Revision as of 14:33, 17 December 2011

Overview

SqLite allows you to store data in a file and query this data using SQL just as you would do with a database server. As an example if you want to manage your stock transactions selecting all buy transactions from a flat file is tedious. Using sqlite you can just issue something like

select * from transactions where type='buy'

and you do not need a database server.

Files

main.cpp

#include <QtSql>

int main(int argc, char *argv[])
{
    QSqlDatabase db;
    db=QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("sqlite.dat");

    if (db.open()) 
        qDebug() << "success";
    else 
        qDebug() << "failed";
    QSqlQuery query;
    query.exec("create table stocks(id int primary key, name varchar(20))");
    db.commit();
    db.close();
}

sqlite.pro

QT       += core gui sql

TARGET = sqlite
TEMPLATE = app


SOURCES += main.cpp

Build it

To build the example project, use the command

qmake && make -j4

Run it

To run the example project, first delete sqlite.dat from your home directory. We do this to show that our example program creates it.

rm ~/sqlite.dat

Then run our example program:

./sqlite

And you will find the database file in your home folder:

ll /root/sqlite.dat 
-rw-r--r-- 1 root root 3072 Nov 10 10:37 /root/sqlite.dat

Analyze it

You can now use the command sqlite3 to analyze your database file:

# sqlite3 sqlite.dat 
SQLite version 3.7.8 2011-09-19 14:49:19
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .schema stocks
CREATE TABLE stocks(id int primary key, name varchar(20));

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