有的时候需要用qt访问sqlite数据库。Linux下一般就用这个数据库，那么如何操作呢？
qt默认支持sql数据库，因此只需要编程即可。注意pro文件中加入QT+=sql。代码如下：
#include<QApplication>
#include<QtSql/QtSql>
int main(int argc,char* argv[])
{
QApplication app(argc,argv);
//一个数据库可以有多个连接,这是一个默认连接,因为没有名字
QSqlDatabase database = QSqlDatabase::addDatabase("QSQLITE");
database.setDatabaseName("database.db");
database.setUserName("root");
database.setPassword("123456");
//打开数据库
if(!database.open())
{
qDebug()<<database.lastError();
qDebug()<<"failed to connect.";
}
else
{
QSqlQuery sql_query;
QString create_sql = "create table student (id int primary key, name varchar(30), age int)";
QString select_max_sql = "select max(id) from student";
QString insert_sql = "insert into student values (?, ?, ?)";
QString update_sql = "update student set name = :name where id = :id";
QString select_sql = "select id, name from student";
QString select_all_sql = "select * from student";
QString delete_sql = "delete from student where id = ?";
QString clear_sql = "delete from student";
sql_query.prepare(create_sql);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
qDebug()<<"table created!";
}
//查询最大id
int max_id = 0;
sql_query.prepare(select_max_sql);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
while(sql_query.next())
{
max_id = sql_query.value(0).toInt();
qDebug()<<QString("max id:%1").arg(max_id);
}
}
//插入数据
sql_query.prepare(insert_sql);
sql_query.addBindValue(max_id+1);
sql_query.addBindValue("name");
sql_query.addBindValue(25);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
qDebug()<<"inserted!";
}
//更新数据
sql_query.prepare(update_sql);
sql_query.bindValue(":name", "Qt");
sql_query.bindValue(":id", 1);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
qDebug()<<"updated!";
}
//查询部分数据
if(!sql_query.exec(select_sql))
{
qDebug()<<sql_query.lastError();
}
else
{
while(sql_query.next())
{
int id = sql_query.value(0).toInt();
QString name = sql_query.value(1).toString();
qDebug()<<QString("id:%1,name:%2").arg(id).arg(name);
}
}
//查询所有数据
sql_query.prepare(select_all_sql);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
while(sql_query.next())
{
int id = sql_query.value(0).toInt();
QString name = sql_query.value(1).toString();
int age = sql_query.value(2).toInt();
qDebug()<<QString("id:%1,name:%2,age:%3").arg(id).arg(name).arg(age);
}
}
//删除数据
sql_query.prepare(delete_sql);
sql_query.addBindValue(max_id);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
qDebug()<<"deleted!";
}
//清空表
sql_query.prepare(clear_sql);
if(!sql_query.exec())
{
qDebug()<<sql_query.lastError();
}
else
{
qDebug()<<"cleared";
}
}
//关闭数据库
database.close();
//删除数据库
QFile::remove("database.db");
return app.exec();
}