C++ QSqlRelation::isValid方法代码示例

/*!
    \reimp
*/
QString QSqlRelationalTableModel::orderByClause() const
{
    Q_D(const QSqlRelationalTableModel);

    const QSqlRelation rel = d->relations.value(d->sortColumn).rel;
    if (!rel.isValid())
        return QSqlTableModel::orderByClause();

    QString f = d->fullyQualifiedFieldName(Sql::relTablePrefix(d->sortColumn), rel.displayColumn());
    f = d->sortOrder == Qt::AscendingOrder ? Sql::asc(f) : Sql::desc(f);
    return Sql::orderBy(f);
}

/*!
    \reimp
*/
QString QSqlRelationalTableModel::orderByClause() const
{
    Q_D(const QSqlRelationalTableModel);

    const QSqlRelation rel = d->relations.value(d->sortColumn).rel;
    if (!rel.isValid())
        return QSqlTableModel::orderByClause();

    QString s = QLatin1String("ORDER BY ");
    s.append(d->relationField(QLatin1String("relTblAl_") + QString::number(d->sortColumn),
                              rel.displayColumn()));
    s += d->sortOrder == Qt::AscendingOrder ? QLatin1String(" ASC") : QLatin1String(" DESC");
    return s;
}

/*!
    \reimp
*/
QString QSqlRelationalTableModel::selectStatement() const
{
    Q_D(const QSqlRelationalTableModel);
    QString query;

    if (tableName().isEmpty())
        return query;
    if (d->relations.isEmpty())
        return QSqlTableModel::selectStatement();

    QString tList;
    QString fList;
    QString where;

    QSqlRecord rec = d->baseRec;
    QStringList tables;
    const QRelation nullRelation;

    // Count how many times each field name occurs in the record
    QHash<QString, int> fieldNames;
    QStringList fieldList;
    for (int i = 0; i < rec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i, nullRelation).rel;
        QString name;
        if (relation.isValid())
        {
            // Count the display column name, not the original foreign key
            name = relation.displayColumn();
            if (d->db.driver()->isIdentifierEscaped(name, QSqlDriver::FieldName))
                name = d->db.driver()->stripDelimiters(name, QSqlDriver::FieldName);

            QSqlRecord rec = database().record(relation.tableName());
            for (int i = 0; i < rec.count(); ++i) {
                if (name.compare(rec.fieldName(i), Qt::CaseInsensitive) == 0) {
                    name = rec.fieldName(i);
                    break;
                }
            }
        }
        else
            name = rec.fieldName(i);
        fieldNames.insert(name, fieldNames.value(name, 0) + 1);
        fieldList.append(name);
    }

    for (int i = 0; i < rec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i, nullRelation).rel;
        if (relation.isValid()) {
            QString relTableAlias = QString::fromLatin1("relTblAl_%1").arg(i);
            if (!fList.isEmpty())
                fList.append(QLatin1String(", "));
            fList.append(d->relationField(relTableAlias,relation.displayColumn()));

            // If there are duplicate field names they must be aliased
            if (fieldNames.value(fieldList[i]) > 1) {
                QString relTableName = relation.tableName().section(QChar::fromLatin1('.'), -1, -1);
                if (d->db.driver()->isIdentifierEscaped(relTableName, QSqlDriver::TableName))
                    relTableName = d->db.driver()->stripDelimiters(relTableName, QSqlDriver::TableName);
                QString displayColumn = relation.displayColumn();
                if (d->db.driver()->isIdentifierEscaped(displayColumn, QSqlDriver::FieldName))
                    displayColumn = d->db.driver()->stripDelimiters(displayColumn, QSqlDriver::FieldName);
                fList.append(QString::fromLatin1(" AS %1_%2_%3").arg(relTableName).arg(displayColumn).arg(fieldNames.value(fieldList[i])));
                fieldNames.insert(fieldList[i], fieldNames.value(fieldList[i])-1);
            }

            // this needs fixing!! the below if is borken.
            tables.append(relation.tableName().append(QLatin1Char(' ')).append(relTableAlias));
            if(!where.isEmpty())
                where.append(QLatin1String(" AND "));
            where.append(d->relationField(tableName(), d->db.driver()->escapeIdentifier(rec.fieldName(i), QSqlDriver::FieldName)));
            where.append(QLatin1String(" = "));
            where.append(d->relationField(relTableAlias, relation.indexColumn()));
        } else {
            if (!fList.isEmpty())
                fList.append(QLatin1String(", "));
            fList.append(d->relationField(tableName(), d->db.driver()->escapeIdentifier(rec.fieldName(i), QSqlDriver::FieldName)));
        }
    }
    if (!tables.isEmpty())
        tList.append(tables.join(QLatin1String(", ")));
    if (fList.isEmpty())
        return query;
    if(!tList.isEmpty())
        tList.prepend(QLatin1String(", "));
    tList.prepend(tableName());
    query.append(QLatin1String("SELECT "));
    query.append(fList).append(QLatin1String(" FROM ")).append(tList);
    qAppendWhereClause(query, where, filter());

    QString orderBy = orderByClause();
    if (!orderBy.isEmpty())
        query.append(QLatin1Char(' ')).append(orderBy);

    return query;
}

bool QRelation::isValid()
{
    return (rel.isValid() && m_parent != NULL);
}

/*!
    \reimp
*/
QString QSqlRelationalTableModel::selectStatement() const
{
    Q_D(const QSqlRelationalTableModel);

    if (tableName().isEmpty())
        return QString();
    if (d->relations.isEmpty())
        return QSqlTableModel::selectStatement();

    // Count how many times each field name occurs in the record
    QHash<QString, int> fieldNames;
    QStringList fieldList;
    for (int i = 0; i < d->baseRec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i).rel;
        QString name;
        if (relation.isValid()) {
            // Count the display column name, not the original foreign key
            name = relation.displayColumn();
            if (d->db.driver()->isIdentifierEscaped(name, QSqlDriver::FieldName))
                name = d->db.driver()->stripDelimiters(name, QSqlDriver::FieldName);

            const QSqlRecord rec = database().record(relation.tableName());
            for (int i = 0; i < rec.count(); ++i) {
                if (name.compare(rec.fieldName(i), Qt::CaseInsensitive) == 0) {
                    name = rec.fieldName(i);
                    break;
                }
            }
        }
        else {
            name = d->baseRec.fieldName(i);
        }
        fieldNames[name] = fieldNames.value(name, 0) + 1;
        fieldList.append(name);
    }

    QString fList;
    QString conditions;
    QString from = Sql::from(tableName());
    for (int i = 0; i < d->baseRec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i).rel;
        const QString tableField = d->fullyQualifiedFieldName(tableName(), d->db.driver()->escapeIdentifier(d->baseRec.fieldName(i), QSqlDriver::FieldName));
        if (relation.isValid()) {
            const QString relTableAlias = Sql::relTablePrefix(i);
            QString displayTableField = d->fullyQualifiedFieldName(relTableAlias, relation.displayColumn());

            // Duplicate field names must be aliased
            if (fieldNames.value(fieldList[i]) > 1) {
                QString relTableName = relation.tableName().section(QChar::fromLatin1('.'), -1, -1);
                if (d->db.driver()->isIdentifierEscaped(relTableName, QSqlDriver::TableName))
                    relTableName = d->db.driver()->stripDelimiters(relTableName, QSqlDriver::TableName);
                QString displayColumn = relation.displayColumn();
                if (d->db.driver()->isIdentifierEscaped(displayColumn, QSqlDriver::FieldName))
                    displayColumn = d->db.driver()->stripDelimiters(displayColumn, QSqlDriver::FieldName);
                const QString alias = QString::fromLatin1("%1_%2_%3").arg(relTableName).arg(displayColumn).arg(fieldNames.value(fieldList[i]));
                displayTableField = Sql::as(displayTableField, alias);
                --fieldNames[fieldList[i]];
            }

            fList = Sql::comma(fList, displayTableField);

            // Join related table
            const QString tblexpr = Sql::concat(relation.tableName(), relTableAlias);
            const QString relTableField = d->fullyQualifiedFieldName(relTableAlias, relation.indexColumn());
            const QString cond = Sql::eq(tableField, relTableField);
            if (d->joinMode == QSqlRelationalTableModel::InnerJoin) {
                // FIXME: InnerJoin code is known to be broken.
                // Use LeftJoin mode if you want correct behavior.
                from = Sql::comma(from, tblexpr);
                conditions = Sql::et(conditions, cond);
            } else {
                from = Sql::concat(from, Sql::leftJoin(tblexpr));
                from = Sql::concat(from, Sql::on(cond));
            }
        } else {
            fList = Sql::comma(fList, tableField);
        }
    }

    if (fList.isEmpty())
        return QString();

    const QString stmt = Sql::concat(Sql::select(fList), from);
    const QString where = Sql::where(Sql::et(Sql::paren(conditions), Sql::paren(filter())));
    return Sql::concat(Sql::concat(stmt, where), orderByClause());
}

/*!
    \reimp
*/
QString QSqlRelationalTableModel::selectStatement() const
{
    Q_D(const QSqlRelationalTableModel);
    QString query;

    if (tableName().isEmpty())
        return query;
    if (d->relations.isEmpty())
        return QSqlTableModel::selectStatement();

    QString tList;
    QString fList;
    QString where;

    QSqlRecord rec = d->baseRec;
    QStringList tables;
    const QRelation nullRelation;

    // Count how many times each field name occurs in the record
    QHash<QString, int> fieldNames;
    for (int i = 0; i < rec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i, nullRelation).rel;
        QString name;
        if (relation.isValid())
            // Count the display column name, not the original foreign key
            name = relation.displayColumn();
        else
            name = rec.fieldName(i);
        fieldNames.insert(name, fieldNames.value(name, 0) + 1);
    }

    for (int i = 0; i < rec.count(); ++i) {
        QSqlRelation relation = d->relations.value(i, nullRelation).rel;
        if (relation.isValid()) {
            QString relTableAlias = QString::fromLatin1("relTblAl_%1").arg(i);
            fList.append(d->escapedRelationField(relTableAlias, relation.displayColumn()));
            
            // If there are duplicate field names they must be aliased
            if (fieldNames.value(relation.displayColumn()) > 1)
                fList.append(QString::fromLatin1(" AS %1_%2").arg(relation.tableName()).arg(relation.displayColumn()));

            fList.append(QLatin1Char(','));
            if (!tables.contains(relation.tableName()))
                tables.append(d->db.driver()->escapeIdentifier(relation.tableName(),
                       QSqlDriver::TableName).append(QLatin1String(" ")).append(
                       d->db.driver()->escapeIdentifier(relTableAlias, QSqlDriver::TableName)));
            where.append(d->escapedRelationField(tableName(), rec.fieldName(i)));
            where.append(QLatin1Char('='));
            where.append(d->escapedRelationField(relTableAlias, relation.indexColumn()));
            where.append(QLatin1String(" AND "));
        } else {
            fList.append(d->escapedRelationField(tableName(), rec.fieldName(i)));
            fList.append(QLatin1Char(','));
        }
    }
    if (!tables.isEmpty())
        tList.append(tables.join(QLatin1String(","))).append(QLatin1String(","));
    if (fList.isEmpty())
        return query;
    tList.prepend(QLatin1Char(',')).prepend(d->db.driver()->escapeIdentifier(tableName(),
                QSqlDriver::TableName));
    // truncate tailing comma
    tList.chop(1);
    fList.chop(1);
    query.append(QLatin1String("SELECT "));
    query.append(fList).append(QLatin1String(" FROM ")).append(tList);
    if (!where.isEmpty())
        where.chop(5);
    qAppendWhereClause(query, where, filter());

    QString orderBy = orderByClause();
    if (!orderBy.isEmpty())
        query.append(QLatin1Char(' ')).append(orderBy);

    return query;
}