我在一个包含这些代码的类中有两个方法,首先在方法GetDefinitionOfWord中,我被称为GetDictionaryFilePath,可以正确返回DB的名称,但是在方法GetDefinitionOfWord中,执行db.setDatabaseName(GetDictionaryFilePath(ID))时;

它没有设置数据库名称,也无法打开数据库,并且会出现错误,我该如何解决?

请帮我

    QString Dictionary_Operation::GetDefinitionOfWord(QString ID, QString Word)
    {
        QString Result = "";
        QString FinalResult = "";
        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");

        QString DBOpenErrorTitle = QString::fromStdString("Error");
        QString DBOpenErrorMessage = QString::fromStdString("Access denied.");


        QString FileName = GetDictionaryFilePath(ID);

            db.setDatabaseName(GetDictionaryFilePath(ID));

        if (QFile::exists(QString::fromStdString(".\\" + FileName.toStdString()))) {
                    db.setDatabaseName(GetDictionaryFilePath(ID));
                    if (!db.open()) {
                        QMessageBox::critical(0, DBOpenErrorTitle, DBOpenErrorMessage,
                                QMessageBox::Cancel);

                    }
                    else
                    {

             QSqlQuery query;
            query.exec(QString::fromStdString("PRAGMA encoding = UTF-16"));

            QString s = QString::fromStdString("SELECT Definition FROM Dictionary_Words WHERE HeadWord = '%1'").arg(ID);
           QSqlQuery sql(s, db);
            while ( sql.next() )
            {
                  Result =  Result.append(sql.record().value(0).toString());
            }

            db.close();
                FinalResult = ReplaceImageToBase64(Result, ID);
            }
        }
        QSqlDatabase::removeDatabase(FileName);

        return FinalResult;
    }

其他方法是:
      QString Dictionary_Operation::GetDictionaryFilePath(QString ID)
        {
            QString Result = "0";
            QSqlDatabase dbGetDictionaryFilePath =  QSqlDatabase::addDatabase("QSQLITE");

            QString DBOpenErrorTitle = QString::fromStdString("Error");
            QString DBOpenErrorMessage = QString::fromStdString("Access denied.");


            if (QFile::exists(".\\1.pldb")) {
                        dbGetDictionaryFilePath.setDatabaseName(QString::fromStdString("1.pldb"));
                        if (!dbGetDictionaryFilePath.open()) {
                            QMessageBox::critical(0, DBOpenErrorTitle, DBOpenErrorMessage,
                                    QMessageBox::Cancel);

                        }
                        else
                        {

                 QSqlQuery query;
                query.exec(QString::fromStdString("PRAGMA encoding = UTF-16"));


                QString s = QString::fromStdString("SELECT FileName FROM Dictionaries WHERE ID = %1").arg(ID);
               QSqlQuery sql(s, dbGetDictionaryFilePath);
                while ( sql.next() )
                {
                      Result =  sql.record().value(0).toString();
                }

               // dbGetDictionaryFilePath.close();

                }
            }
            QSqlDatabase::removeDatabase(QString::fromStdString("1.pldb"));

            return Result;
        }

最佳答案

您使用相同的连接两次,并且配置部分重叠。因此,当您调用setDatabaseName时,就是在您的GetDictionaryFilePath函数已经打开的连接上调用它。

您应该使用2个不同的连接名称:

QString Dictionary_Operation::GetDefinitionOfWord(QString ID, QString Word)
{
    ...
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "Definitions");

    QString FileName = GetDictionaryFilePath(ID);
    db.setDatabaseName(FileName);
    ...
    // Remove with the name of the connection (and not databaseName())
    QSqlDatabase::removeDatabase("Definitions");
    ...
}

QString Dictionary_Operation::GetDictionaryFilePath(QString ID)
{
    QSqlDatabase dbGetDictionaryFilePath =
        QSqlDatabase::addDatabase("QSQLITE", "Dictionaries");
    ...
        dbGetDictionaryFilePath.setDatabaseName("1.pldb");
    ...
    QSqlDatabase::removeDatabase("Dictionaries");
}

或者,您可以通过在第一个函数中将FileName而不是字符串"Definitions"传递给addDatabaseremoveDatabase来为每个不同的“定义”数据库使用一个连接名称。

PS:为什么使用QString::fromStdString?您可以将文字字符串直接传递给需要const QString &的函数(并且您已经为addDatabase("QSQLITE")完成了此操作)。

08-06 21:34