Qt5.4.1 无法连接SqlServer

QSqlDatabase db;

QString servername="(local)";

QString dbname="QtSqlTest";
db = QSqlDatabase::addDatabase("QODBC");

QString dsn=QString("DRIVER={SQL SERVER};SERVER=%1;DATABASE=%2;").arg(servername).arg(dbname);

db.setDatabaseName(dsn);

db.setUserName("sa");

db.setPassword("123456");


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