qt怎样创建数据库以及数据库的操作

QT创建和插入的操作代码如下：
bool database::createDatabase()
{
QSqlQuery query; // 此处请查询 query的相关操作
qDebug() << "Start to create table...";
//create table: User
query.exec("CREATE TABLE [User] ( [userId] VARCHAR(40) NOT NULL, [username] VARCHAR(40) NOT NULL, [email] VARCHAR(40), [password] VARCHAR(40), [city] VARCHAR(20), PRIMARY KEY([userId]) )"); // 一定注意不要拼写错误，引号内是不提示拼写错误的。
//create table: Connect
query.exec("CREATE TABLE [Connect] ( [LeftUser] VARCHAR(40) NOT NULL, [RightUser] VARCHAR(40) NOT NULL, [relation] INTEGER DEFAULT '0' NULL, PRIMARY KEY ([LeftUser], [RightUser]))");
if (query.lastError().isValid())
{
qDebug() << query.lastError();
return false;
}
else
{
qDebug() << "Create database successfully.";
}
return true;
}
插入操作

bool database::adduser( User user )
{
if (!db.isOpen())
{
createconnection();
}
QSqlQuery query;
qDebug() << "start to insert data";
query.exec("INSERT INTO [User] ( userId, username, email, password, city) VALUES(?,?,?,?,?)");
QVariantList userId;
userId << user.getUserId();
query.addBindValue(userId);
QVariantList username;
username << user.getUserName();
query.addBindValue(username);
QVariantList email;
email << user.getEmail();
query.addBindValue(email);
QVariantList password;
password << user.getPassword();
query.addBindValue(password);
QVariantList city;
city << user.getCity();
query.addBindValue(city);
try
{
if (!query.execBatch())
{
qDebug() << query.lastQuery();
qDebug() << query.lastError();
return NULL;
}
}
catch(...)
{
QMessageBox::critical(0, "Add New Node error!",
"Unable to add a new Node!/n/n"
"Click Cancel to exit.", QMessageBox::Cancel);
}
if( !UpdateConnectTable(user.getUserId(),user.getUserId(),2))
{
QMessageBox::critical(0,"","Update table Connect error");
return NULL;
}
return true;
}

qt可以实现连接各种数据库，这里介绍qt自带的一种数据库（Qsqlite）#include#include#include#include#include#include#includestaticboolcreateConnection(){QSqlDatabasedb=QSqlDatabase::addDatabase("QSQLITE");db.setDatabaseName("mytest.db");if(!db.open())returnfalse;QSqlQueryquery;//query.exec(QObject::tr("createtablestudent(idintprimarykey,namevchar)"));//query.exec(QObject::tr("insertintostudentvalues(0,'刘')"));////query.exec(QObject::tr("insertintostudentvalues(1,'刚')"));//query.exec(QObject::tr("insertintostudentvalues(2,'红')"));//query.prepare("insertintostudentvalues(?,?)");//-------------------------------------------------------//通过下面这段代码可以实现向数据库插入变量//--------------------------------------------------------QVariantListages;intx1,x2,x3,x4;x1=12;x2=13;x3=14;x4=15;ages<