链接mysql数据库出现QSqlError(-1, "", "")这种错误，数据库是连上了，但是查询的时候总是出现这种错误：这是代码：
int main(int argc, char *argv[])
{
QApplication a(argc,argv);
QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
db.setHostName("localhost");
db.setDatabaseName("test");
db.setUserName("root");
db.setPassword("");
if(!db.open()) //打开数据库
{
qDebug()<<"cant't open\n";
qDebug()<<db.lastError();
}
QSqlQuery query;
query.exec("create table student(id int primary key,name varchar)");
query.exec("insert into student values(1,'hellow')");
query.exec("insert into student values(2,'nihaoa')");
query.exec("insert into student values(3,'baybay')");
query.exec("select * from student");
while(query.next())
{
int ele0 = query.value(0).toInt();
QString ele1 =query.value(1).toString();
qDebug() << ele0 <<ele1;
}
qDebug()<<query.lastError();
return a.exec();
}
