我编辑Qlineedit后,对数据验证,但总运行两次,为什么?
connect(linNo, SIGNAL(editingFinished()), this, SLOT(linNoValidate()));
bool frmAddCapital::linNoValidate()
{
    QString num = linNo->text();
    QSqlQuery query;
    query.exec("Select * From register Where 凭证号码 =" + num);
    if (query.next()) {
        labNo->setFocus();
        QMessageBox::critical(this, "错误","已有#" + num + "号凭证!");
        return true;
    }
    return false;
}