//! [0]
QSqlDatabase db = ...;
QVariant v = db.driver()->handle();
if (v.isValid() && qstrcmp(v.typeName(), "sqlite3*")==0) {
    // v.data() returns a pointer to the handle
    sqlite3 *handle = *static_cast<sqlite3 **>(v.data());
    if (handle != 0) { // check that it is not NULL
        ...
    }
}
//! [0]


//! [1]
if (v.typeName() == "PGconn*") {
    PGconn *handle = *static_cast<PGconn **>(v.data());
    if (handle != 0) ...
}

if (v.typeName() == "MYSQL*") {
    MYSQL *handle = *static_cast<MYSQL **>(v.data());
    if (handle != 0) ...
}
//! [1]