qsqlindex.cpp

奇趣公司比较新的qt/emd版本

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#include "qsqlindex.h"

#include "qsqlfield.h"
#include "qstringlist.h"

/*!
    \class QSqlIndex
    \brief The QSqlIndex class provides functions to manipulate and
    describe database indexes.

    \ingroup database
    \module sql

    An \e index refers to a single table or view in a database.
    Information about the fields that comprise the index can be used
    to generate SQL statements, or to affect the behavior of a
    QSqlCursor object.
*/

/*!
    Constructs an empty index using the cursor name \a cursorname and
    index name \a name.
*/

QSqlIndex::QSqlIndex(const QString& cursorname, const QString& name)
    : cursor(cursorname), nm(name)
{
}

/*!
    Constructs a copy of \a other.
*/

QSqlIndex::QSqlIndex(const QSqlIndex& other)
    : QSqlRecord(other), cursor(other.cursor), nm(other.nm), sorts(other.sorts)
{
}

/*!
    Sets the index equal to \a other.
*/

QSqlIndex& QSqlIndex::operator=(const QSqlIndex& other)
{
    cursor = other.cursor;
    nm = other.nm;
    sorts = other.sorts;
    QSqlRecord::operator=(other);
    return *this;
}

/*!
    Destroys the object and frees any allocated resources.
*/

QSqlIndex::~QSqlIndex()
{

}

/*!
    Sets the name of the index to \a name.
*/

void QSqlIndex::setName(const QString& name)
{
    nm = name;
}

/*!
    \fn QString QSqlIndex::name() const

    Returns the name of the index.
*/

/*!
    Appends the field \a field to the list of indexed fields. The
    field is appended with an ascending sort order.
*/

void QSqlIndex::append(const QSqlField& field)
{
    append(field, false);
}

/*!
    \overload

    Appends the field \a field to the list of indexed fields. The
    field is appended with an ascending sort order, unless \a desc is
    true.
*/

void QSqlIndex::append(const QSqlField& field, bool desc)
{
    sorts.append(desc);
    QSqlRecord::append(field);
}


/*!
    Returns true if field \a i in the index is sorted in descending
    order; otherwise returns false.
*/

bool QSqlIndex::isDescending(int i) const
{
    if (i >= 0 && i < sorts.size())
        return sorts[i];
    return false;
}

/*!
    If \a desc is true, field \a i is sorted in descending order.
    Otherwise, field \a i is sorted in ascending order (the default).
    If the field does not exist, nothing happens.
*/

void QSqlIndex::setDescending(int i, bool desc)
{
    if (i >= 0 && i < sorts.size())
        sorts[i] = desc;
}

#ifdef QT3_SUPPORT

/*!
    Returns a comma-separated list of all the index's field names as a
    string. This string is suitable, for example, for generating a
    SQL SELECT statement. Only generated fields are included in the
    list (see \l{isGenerated()}). If a \a prefix is specified, e.g. a
    table name, it is prepended before all field names in the form:

    "\a{prefix}.<fieldname>"

    If \a sep is specified, each field is separated by \a sep. If \a
    verbose is true (the default), each field contains a suffix
    indicating an ASCending or DESCending sort order.
*/

QString QSqlIndex::toString(const QString& prefix, const QString& sep, bool verbose) const
{
    QString s;
    bool comma = false;
    for (int i = 0; i < count(); ++i) {
        if(comma)
            s += sep + QLatin1Char(' ');
        s += createField(i, prefix, verbose);
        comma = true;
    }
    return s;
}

/*!
    Returns a list of all the index's field names. Only generated
    fields are included in the list (see \l{isGenerated()}). If a \a
    prefix is specified, e.g. a table name, all fields are prefixed in
    the form:

    "\a{prefix}.<fieldname>"

    If \a verbose is true (the default), each field contains a suffix
    indicating an ASCending or DESCending sort order.

    Note that if you want to iterate over the list, you should iterate
    over a copy, e.g.
    \code
    QStringList list = myIndex.toStringList();
    QStringList::Iterator it = list.begin();
    while(it != list.end()) {
        myProcessing(*it);
        ++it;
    }
    \endcode

*/
QStringList QSqlIndex::toStringList(const QString& prefix, bool verbose) const
{
    QStringList s;
    for (int i = 0; i < count(); ++i)
        s += createField(i, prefix, verbose);
    return s;
}
#endif

/*! \internal

  Creates a string representing the field number \a i using prefix \a
  prefix. If \a verbose is true, ASC or DESC is included in the field
  description if the field is sorted in ASCending or DESCending order.
*/

QString QSqlIndex::createField(int i, const QString& prefix, bool verbose) const
{
    QString f;
    if (!prefix.isEmpty())
        f += prefix + QLatin1Char('.');
    f += field(i).name();
    if (verbose)
        f += QLatin1Char(' ') + QString((isDescending(i)
                    ? QLatin1String("DESC") : QLatin1String("ASC")));
    return f;
}

/*!
    \fn QString QSqlIndex::cursorName() const

    Returns the name of the cursor which the index is associated with.
*/


/*!
    Sets the name of the cursor that the index is associated with to
    \a cursorName.
*/
void QSqlIndex::setCursorName(const QString& cursorName)
{
    cursor = cursorName;
}