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#include "qsqlquery.h"
//#define QT_DEBUG_SQL
#include "qatomic.h"
#include "qsqlrecord.h"
#include "qsqlresult.h"
#include "qsqldriver.h"
#include "qsqldatabase.h"
#include "private/qsqlnulldriver_p.h"
#include "qvector.h"
#include "qmap.h"
QT_BEGIN_NAMESPACE
class QSqlQueryPrivate
{
public:
QSqlQueryPrivate(QSqlResult* result);
~QSqlQueryPrivate();
QAtomicInt ref;
QSqlResult* sqlResult;
static QSqlQueryPrivate* shared_null();
};
Q_GLOBAL_STATIC_WITH_ARGS(QSqlQueryPrivate, nullQueryPrivate, (0))
Q_GLOBAL_STATIC(QSqlNullDriver, nullDriver)
Q_GLOBAL_STATIC_WITH_ARGS(QSqlNullResult, nullResult, (nullDriver()))
QSqlQueryPrivate* QSqlQueryPrivate::shared_null()
{
QSqlQueryPrivate *null = nullQueryPrivate();
null->ref.ref();
return null;
}
/*!
\internal
*/
QSqlQueryPrivate::QSqlQueryPrivate(QSqlResult* result)
: ref(1), sqlResult(result)
{
if (!sqlResult)
sqlResult = nullResult();
}
QSqlQueryPrivate::~QSqlQueryPrivate()
{
QSqlResult *nr = nullResult();
if (!nr || sqlResult == nr)
return;
delete sqlResult;
}
/*!
\class QSqlQuery
\brief The QSqlQuery class provides a means of executing and
manipulating SQL statements.
\ingroup database
\ingroup shared
\inmodule QtSql
QSqlQuery encapsulates the functionality involved in creating,
navigating and retrieving data from SQL queries which are
executed on a \l QSqlDatabase. It can be used to execute DML
(data manipulation language) statements, such as \c SELECT, \c
INSERT, \c UPDATE and \c DELETE, as well as DDL (data definition
language) statements, such as \c{CREATE} \c{TABLE}. It can also
be used to execute database-specific commands which are not
standard SQL (e.g. \c{SET DATESTYLE=ISO} for PostgreSQL).
Successfully executed SQL statements set the query's state to
active so that isActive() returns true. Otherwise the query's
state is set to inactive. In either case, when executing a new SQL
statement, the query is positioned on an invalid record. An active
query must be navigated to a valid record (so that isValid()
returns true) before values can be retrieved.
For some databases, if an active query that is a \c{SELECT}
statement exists when you call \l{QSqlDatabase::}{commit()} or
\l{QSqlDatabase::}{rollback()}, the commit or rollback will
fail. See isActive() for details.
\target QSqlQuery examples
Navigating records is performed with the following functions:
\list
\o next()
\o previous()
\o first()
\o last()
\o seek()
\endlist
These functions allow the programmer to move forward, backward
or arbitrarily through the records returned by the query. If you
only need to move forward through the results (e.g., by using
next()), you can use setForwardOnly(), which will save a
significant amount of memory overhead and improve performance on
some databases. Once an active query is positioned on a valid
record, data can be retrieved using value(). All data is
transferred from the SQL backend using QVariants.
For example:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 7
To access the data returned by a query, use value(int). Each
field in the data returned by a \c SELECT statement is accessed
by passing the field's position in the statement, starting from
0. This makes using \c{SELECT *} queries inadvisable because the
order of the fields returned is indeterminate.
For the sake of efficiency, there are no functions to access a
field by name (unless you use prepared queries with names, as
explained below). To convert a field name into an index, use
record().\l{QSqlRecord::indexOf()}{indexOf()}, for example:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 8
QSqlQuery supports prepared query execution and the binding of
parameter values to placeholders. Some databases don't support
these features, so for those, Qt emulates the required
functionality. For example, the Oracle and ODBC drivers have
proper prepared query support, and Qt makes use of it; but for
databases that don't have this support, Qt implements the feature
itself, e.g. by replacing placeholders with actual values when a
query is executed. Use numRowsAffected() to find out how many rows
were affected by a non-\c SELECT query, and size() to find how
many were retrieved by a \c SELECT.
Oracle databases identify placeholders by using a colon-name
syntax, e.g \c{:name}. ODBC simply uses \c ? characters. Qt
supports both syntaxes, with the restriction that you can't mix
them in the same query.
You can retrieve the values of all the fields in a single variable
(a map) using boundValues().
\section1 Approaches to Binding Values
Below we present the same example using each of the four
different binding approaches, as well as one example of binding
values to a stored procedure.
\bold{Named binding using named placeholders:}
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 9
\bold{Positional binding using named placeholders:}
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 10
\bold{Binding values using positional placeholders (version 1):}
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 11
\bold{Binding values using positional placeholders (version 2):}
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 12
\bold{Binding values to a stored procedure:}
This code calls a stored procedure called \c AsciiToInt(), passing
it a character through its in parameter, and taking its result in
the out parameter.
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 13
Note that unbound parameters will retain their values.
Stored procedures that uses the return statement to return values,
or return multiple result sets, are not fully supported. For specific
details see \l{SQL Database Drivers}.
\warning You must load the SQL driver and open the connection before a
QSqlQuery is created. Also, the connection must remain open while the
query exists; otherwise, the behavior of QSqlQuery is undefined.
\sa QSqlDatabase, QSqlQueryModel, QSqlTableModel, QVariant
*/
/*!
Constructs a QSqlQuery object which uses the QSqlResult \a result
to communicate with a database.
*/
QSqlQuery::QSqlQuery(QSqlResult *result)
{
d = new QSqlQueryPrivate(result);
}
/*!
Destroys the object and frees any allocated resources.
*/
QSqlQuery::~QSqlQuery()
{
if (!d->ref.deref())
delete d;
}
/*!
Constructs a copy of \a other.
*/
QSqlQuery::QSqlQuery(const QSqlQuery& other)
{
d = other.d;
d->ref.ref();
}
/*!
\internal
*/
static void qInit(QSqlQuery *q, const QString& query, QSqlDatabase db)
{
QSqlDatabase database = db;
if (!database.isValid())
database = QSqlDatabase::database(QLatin1String(QSqlDatabase::defaultConnection), false);
if (database.isValid()) {
*q = QSqlQuery(database.driver()->createResult());
}
if (!query.isEmpty())
q->exec(query);
}
/*!
Constructs a QSqlQuery object using the SQL \a query and the
database \a db. If \a db is not specified, the application's
default database is used. If \a query is not an empty string, it
will be executed.
\sa QSqlDatabase
*/
QSqlQuery::QSqlQuery(const QString& query, QSqlDatabase db)
{
d = QSqlQueryPrivate::shared_null();
qInit(this, query, db);
}
/*!
Constructs a QSqlQuery object using the database \a db.
\sa QSqlDatabase
*/
QSqlQuery::QSqlQuery(QSqlDatabase db)
{
d = QSqlQueryPrivate::shared_null();
qInit(this, QString(), db);
}
/*!
Assigns \a other to this object.
*/
QSqlQuery& QSqlQuery::operator=(const QSqlQuery& other)
{
qAtomicAssign(d, other.d);
return *this;
}
/*!
Returns true if the query is \l{isActive()}{active} and positioned
on a valid record and the \a field is NULL; otherwise returns
false. Note that for some drivers, isNull() will not return accurate
information until after an attempt is made to retrieve data.
\sa isActive(), isValid(), value()
*/
bool QSqlQuery::isNull(int field) const
{
if (d->sqlResult->isActive() && d->sqlResult->isValid())
return d->sqlResult->isNull(field);
return true;
}
/*!
Executes the SQL in \a query. Returns true and sets the query state
to \l{isActive()}{active} if the query was successful; otherwise
returns false. The \a query string must use syntax appropriate for
the SQL database being queried (for example, standard SQL).
After the query is executed, the query is positioned on an \e
invalid record and must be navigated to a valid record before data
values can be retrieved (for example, using next()).
Note that the last error for this query is reset when exec() is
called.
Example:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 34
\sa isActive(), isValid(), next(), previous(), first(), last(),
seek()
*/
bool QSqlQuery::exec(const QString& query)
{
if (d->ref != 1) {
bool fo = isForwardOnly();
*this = QSqlQuery(driver()->createResult());
d->sqlResult->setNumericalPrecisionPolicy(d->sqlResult->numericalPrecisionPolicy());
setForwardOnly(fo);
} else {
d->sqlResult->clear();
d->sqlResult->setActive(false);
d->sqlResult->setLastError(QSqlError());
d->sqlResult->setAt(QSql::BeforeFirstRow);
d->sqlResult->setNumericalPrecisionPolicy(d->sqlResult->numericalPrecisionPolicy());
}
d->sqlResult->setQuery(query.trimmed());
if (!driver()->isOpen() || driver()->isOpenError()) {
qWarning("QSqlQuery::exec: database not open");
return false;
}
if (query.isEmpty()) {
qWarning("QSqlQuery::exec: empty query");
return false;
}
#ifdef QT_DEBUG_SQL
qDebug("\n QSqlQuery: %s", query.toLocal8Bit().constData());
#endif
return d->sqlResult->reset(query);
}
/*!
Returns the value of field \a index in the current record.
The fields are numbered from left to right using the text of the
\c SELECT statement, e.g. in
\snippet doc/src/snippets/code/src_sql_kernel_qsqlquery.cpp 0
field 0 is \c forename and field 1 is \c
surname. Using \c{SELECT *} is not recommended because the order
of the fields in the query is undefined.
An invalid QVariant is returned if field \a index does not
exist, if the query is inactive, or if the query is positioned on
an invalid record.
\sa previous() next() first() last() seek() isActive() isValid()
*/
QVariant QSqlQuery::value(int index) const
{
if (isActive() && isValid() && (index > QSql::BeforeFirstRow))
return d->sqlResult->data(index);
qWarning("QSqlQuery::value: not positioned on a valid record");
return QVariant();
}
/*!
Returns the current internal position of the query. The first
record is at position zero. If the position is invalid, the
function returns QSql::BeforeFirstRow or
QSql::AfterLastRow, which are special negative values.
\sa previous() next() first() last() seek() isActive() isValid()
*/
int QSqlQuery::at() const
{
return d->sqlResult->at();
}
/*!
Returns the text of the current query being used, or an empty
string if there is no current query text.
\sa executedQuery()
*/
QString QSqlQuery::lastQuery() const
{
return d->sqlResult->lastQuery();
}
/*!
Returns the database driver associated with the query.
*/
const QSqlDriver *QSqlQuery::driver() const
{
return d->sqlResult->driver();
}
/*!
Returns the result associated with the query.
*/
const QSqlResult* QSqlQuery::result() const
{
return d->sqlResult;
}
/*!
Retrieves the record at position \a index, if available, and
positions the query on the retrieved record. The first record is at
position 0. Note that the query must be in an \l{isActive()}
{active} state and isSelect() must return true before calling this
function.
If \a relative is false (the default), the following rules apply:
\list
\o If \a index is negative, the result is positioned before the
first record and false is returned.
\o Otherwise, an attempt is made to move to the record at position
\a index. If the record at position \a index could not be retrieved,
the result is positioned after the last record and false is
returned. If the record is successfully retrieved, true is returned.
\endlist
If \a relative is true, the following rules apply:
\list
\o If the result is currently positioned before the first record or
on the first record, and \a index is negative, there is no change,
and false is returned.
\o If the result is currently located after the last record, and \a
index is positive, there is no change, and false is returned.
\o If the result is currently located somewhere in the middle, and
the relative offset \a index moves the result below zero, the result
is positioned before the first record and false is returned.
\o Otherwise, an attempt is made to move to the record \a index
records ahead of the current record (or \a index records behind the
current record if \a index is negative). If the record at offset \a
index could not be retrieved, the result is positioned after the
last record if \a index >= 0, (or before the first record if \a
index is negative), and false is returned. If the record is
successfully retrieved, true is returned.
\endlist
\sa next() previous() first() last() at() isActive() isValid()
*/
bool QSqlQuery::seek(int index, bool relative)
{
if (!isSelect() || !isActive())
return false;
int actualIdx;
if (!relative) { // arbitrary seek
if (index < 0) {
d->sqlResult->setAt(QSql::BeforeFirstRow);
return false;
}
actualIdx = index;
} else {
switch (at()) { // relative seek
case QSql::BeforeFirstRow:
if (index > 0)
actualIdx = index;
else {
return false;
}
break;
case QSql::AfterLastRow:
if (index < 0) {
d->sqlResult->fetchLast();
actualIdx = at() + index;
} else {
return false;
}
break;
default:
if ((at() + index) < 0) {
d->sqlResult->setAt(QSql::BeforeFirstRow);
return false;
}
actualIdx = at() + index;
break;
}
}
// let drivers optimize
if (isForwardOnly() && actualIdx < at()) {
qWarning("QSqlQuery::seek: cannot seek backwards in a forward only query");
return false;
}
if (actualIdx == (at() + 1) && at() != QSql::BeforeFirstRow) {
if (!d->sqlResult->fetchNext()) {
d->sqlResult->setAt(QSql::AfterLastRow);
return false;
}
return true;
}
if (actualIdx == (at() - 1)) {
if (!d->sqlResult->fetchPrevious()) {
d->sqlResult->setAt(QSql::BeforeFirstRow);
return false;
}
return true;
}
if (!d->sqlResult->fetch(actualIdx)) {
d->sqlResult->setAt(QSql::AfterLastRow);
return false;
}
return true;
}
/*!
Retrieves the next record in the result, if available, and positions
the query on the retrieved record. Note that the result must be in
the \l{isActive()}{active} state and isSelect() must return true
before calling this function or it will do nothing and return false.
The following rules apply:
\list
\o If the result is currently located before the first record,
e.g. immediately after a query is executed, an attempt is made to
retrieve the first record.
\o If the result is currently located after the last record, there
is no change and false is returned.
\o If the result is located somewhere in the middle, an attempt is
made to retrieve the next record.
\endlist
If the record could not be retrieved, the result is positioned after
the last record and false is returned. If the record is successfully
retrieved, true is returned.
\sa previous() first() last() seek() at() isActive() isValid()
*/
bool QSqlQuery::next()
{
if (!isSelect() || !isActive())
return false;
bool b = false;
switch (at()) {
case QSql::BeforeFirstRow:
b = d->sqlResult->fetchFirst();
return b;
case QSql::AfterLastRow:
return false;
default:
if (!d->sqlResult->fetchNext()) {
d->sqlResult->setAt(QSql::AfterLastRow);
return false;
}
return true;
}
}
/*!
Retrieves the previous record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in the \l{isActive()}{active} state and isSelect() must
return true before calling this function or it will do nothing and
return false.
The following rules apply:
\list
\o If the result is currently located before the first record, there
is no change and false is returned.
\o If the result is currently located after the last record, an
attempt is made to retrieve the last record.
\o If the result is somewhere in the middle, an attempt is made to
retrieve the previous record.
\endlist
If the record could not be retrieved, the result is positioned
before the first record and false is returned. If the record is
successfully retrieved, true is returned.
\sa next() first() last() seek() at() isActive() isValid()
*/
bool QSqlQuery::previous()
{
if (!isSelect() || !isActive())
return false;
if (isForwardOnly()) {
qWarning("QSqlQuery::seek: cannot seek backwards in a forward only query");
return false;
}
bool b = false;
switch (at()) {
case QSql::BeforeFirstRow:
return false;
case QSql::AfterLastRow:
b = d->sqlResult->fetchLast();
return b;
default:
if (!d->sqlResult->fetchPrevious()) {
d->sqlResult->setAt(QSql::BeforeFirstRow);
return false;
}
return true;
}
}
/*!
Retrieves the first record in the result, if available, and
positions the query on the retrieved record. Note that the result
must be in the \l{isActive()}{active} state and isSelect() must
return true before calling this function or it will do nothing and
return false. Returns true if successful. If unsuccessful the query
position is set to an invalid position and false is returned.
\sa next() previous() last() seek() at() isActive() isValid()
*/
bool QSqlQuery::first()
{
if (!isSelect() || !isActive())
return false;
if (isForwardOnly() && at() > QSql::BeforeFirstRow) {
qWarning("QSqlQuery::seek: cannot seek backwards in a forward only query");
return false;
}
bool b = false;
b = d->sqlResult->fetchFirst();
return b;
}
/*!
Retrieves the last record in the result, if available, and positions
the query on the retrieved record. Note that the result must be in
the \l{isActive()}{active} state and isSelect() must return true
before calling this function or it will do nothing and return false.
Returns true if successful. If unsuccessful the query position is
set to an invalid position and false is returned.
\sa next() previous() first() seek() at() isActive() isValid()
*/
bool QSqlQuery::last()
{
if (!isSelect() || !isActive())
return false;
bool b = false;
b = d->sqlResult->fetchLast();
return b;
}
/*!
Returns the size of the result (number of rows returned), or -1 if
the size cannot be determined or if the database does not support
reporting information about query sizes. Note that for non-\c SELECT
statements (isSelect() returns false), size() will return -1. If the
query is not active (isActive() returns false), -1 is returned.
To determine the number of rows affected by a non-\c SELECT
statement, use numRowsAffected().
\sa isActive() numRowsAffected() QSqlDriver::hasFeature()
*/
int QSqlQuery::size() const
{
if (isActive() && d->sqlResult->driver()->hasFeature(QSqlDriver::QuerySize))
return d->sqlResult->size();
return -1;
}
/*!
Returns the number of rows affected by the result's SQL statement,
or -1 if it cannot be determined. Note that for \c SELECT
statements, the value is undefined; use size() instead. If the query
is not \l{isActive()}{active}, -1 is returned.
\sa size() QSqlDriver::hasFeature()
*/
int QSqlQuery::numRowsAffected() const
{
if (isActive())
return d->sqlResult->numRowsAffected();
return -1;
}
/*!
Returns error information about the last error (if any) that
occurred with this query.
\sa QSqlError, QSqlDatabase::lastError()
*/
QSqlError QSqlQuery::lastError() const
{
return d->sqlResult->lastError();
}
/*!
Returns true if the query is currently positioned on a valid
record; otherwise returns false.
*/
bool QSqlQuery::isValid() const
{
return d->sqlResult->isValid();
}
/*!
Returns true if the query is \e{active}. An active QSqlQuery is one
that has been \l{QSqlQuery::exec()} {exec()'d} successfully but not
yet finished with. When you are finished with an active query, you
can make make the query inactive by calling finish() or clear(), or
you can delete the QSqlQuery instance.
\note Of particular interest is an active query that is a \c{SELECT}
statement. For some databases that support transactions, an active
query that is a \c{SELECT} statement can cause a \l{QSqlDatabase::}
{commit()} or a \l{QSqlDatabase::} {rollback()} to fail, so before
committing or rolling back, you should make your active \c{SELECT}
statement query inactive using one of the ways listed above.
\sa isSelect()
*/
bool QSqlQuery::isActive() const
{
return d->sqlResult->isActive();
}
/*!
Returns true if the current query is a \c SELECT statement;
otherwise returns false.
*/
bool QSqlQuery::isSelect() const
{
return d->sqlResult->isSelect();
}
/*!
Returns true if you can only scroll forward through a result set;
otherwise returns false.
\sa setForwardOnly(), next()
*/
bool QSqlQuery::isForwardOnly() const
{
return d->sqlResult->isForwardOnly();
}
/*!
Sets forward only mode to \a forward. If \a forward is true, only
next() and seek() with positive values, are allowed for navigating
the results.
Forward only mode can be (depending on the driver) more memory
efficient since results do not need to be cached. It will also
improve performance on some databases. For this to be true, you must
call \c setForwardOnly() before the query is prepared or executed.
Note that the constructor that takes a query and a database may
execute the query.
Forward only mode is off by default.
Setting forward only to false is a suggestion to the database engine,
which has the final say on whether a result set is forward only or
scrollable. isForwardOnly() will always return the correct status of
the result set.
\note Calling setForwardOnly after execution of the query will result
in unexpected results at best, and crashes at worst.
\sa isForwardOnly(), next(), seek(), QSqlResult::setForwardOnly()
*/
void QSqlQuery::setForwardOnly(bool forward)
{
d->sqlResult->setForwardOnly(forward);
}
/*!
Returns a QSqlRecord containing the field information for the
current query. If the query points to a valid row (isValid() returns
true), the record is populated with the row's values. An empty
record is returned when there is no active query (isActive() returns
false).
To retrieve values from a query, value() should be used since
its index-based lookup is faster.
In the following example, a \c{SELECT * FROM} query is executed.
Since the order of the columns is not defined, QSqlRecord::indexOf()
is used to obtain the index of a column.
\snippet doc/src/snippets/code/src_sql_kernel_qsqlquery.cpp 1
\sa value()
*/
QSqlRecord QSqlQuery::record() const
{
QSqlRecord rec = d->sqlResult->record();
if (isValid()) {
for (int i = 0; i < rec.count(); ++i)
rec.setValue(i, value(i));
}
return rec;
}
/*!
Clears the result set and releases any resources held by the
query. Sets the query state to inactive. You should rarely if ever
need to call this function.
*/
void QSqlQuery::clear()
{
*this = QSqlQuery(driver()->createResult());
}
/*!
Prepares the SQL query \a query for execution. Returns true if the
query is prepared successfully; otherwise returns false.
The query may contain placeholders for binding values. Both Oracle
style colon-name (e.g., \c{:surname}), and ODBC style (\c{?})
placeholders are supported; but they cannot be mixed in the same
query. See the \l{QSqlQuery examples}{Detailed Description} for
examples.
Portability note: Some databases choose to delay preparing a query
until it is executed the first time. In this case, preparing a
syntactically wrong query succeeds, but every consecutive exec()
will fail.
Example:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 9
\sa exec(), bindValue(), addBindValue()
*/
bool QSqlQuery::prepare(const QString& query)
{
if (d->ref != 1) {
bool fo = isForwardOnly();
*this = QSqlQuery(driver()->createResult());
setForwardOnly(fo);
d->sqlResult->setNumericalPrecisionPolicy(d->sqlResult->numericalPrecisionPolicy());
} else {
d->sqlResult->setActive(false);
d->sqlResult->setLastError(QSqlError());
d->sqlResult->setAt(QSql::BeforeFirstRow);
d->sqlResult->setNumericalPrecisionPolicy(d->sqlResult->numericalPrecisionPolicy());
}
if (!driver()) {
qWarning("QSqlQuery::prepare: no driver");
return false;
}
if (!driver()->isOpen() || driver()->isOpenError()) {
qWarning("QSqlQuery::prepare: database not open");
return false;
}
if (query.isEmpty()) {
qWarning("QSqlQuery::prepare: empty query");
return false;
}
#ifdef QT_DEBUG_SQL
qDebug("\n QSqlQuery::prepare: %s", query.toLocal8Bit().constData());
#endif
return d->sqlResult->savePrepare(query);
}
/*!
Executes a previously prepared SQL query. Returns true if the query
executed successfully; otherwise returns false.
Note that the last error for this query is reset when exec() is
called.
\sa prepare() bindValue() addBindValue() boundValue() boundValues()
*/
bool QSqlQuery::exec()
{
d->sqlResult->resetBindCount();
if (d->sqlResult->lastError().isValid())
d->sqlResult->setLastError(QSqlError());
return d->sqlResult->exec();
}
/*! \enum QSqlQuery::BatchExecutionMode
\value ValuesAsRows - Updates multiple rows. Treats every entry in a QVariantList as a value for updating the next row.
\value ValuesAsColumns - Updates a single row. Treats every entry in a QVariantList as a single value of an array type.
*/
/*!
\since 4.2
Executes a previously prepared SQL query in a batch. All the bound
parameters have to be lists of variants. If the database doesn't
support batch executions, the driver will simulate it using
conventional exec() calls.
Returns true if the query is executed successfully; otherwise
returns false.
Example:
\snippet doc/src/snippets/code/src_sql_kernel_qsqlquery.cpp 2
The example above inserts four new rows into \c myTable:
\snippet doc/src/snippets/code/src_sql_kernel_qsqlquery.cpp 3
To bind NULL values, a null QVariant of the relevant type has to be
added to the bound QVariantList; for example, \c
{QVariant(QVariant::String)} should be used if you are using
strings.
\note Every bound QVariantList must contain the same amount of
variants.
\note The type of the QVariants in a list must not change. For
example, you cannot mix integer and string variants within a
QVariantList.
The \a mode parameter indicates how the bound QVariantList will be
interpreted. If \a mode is \c ValuesAsRows, every variant within
the QVariantList will be interpreted as a value for a new row. \c
ValuesAsColumns is a special case for the Oracle driver. In this
mode, every entry within a QVariantList will be interpreted as
array-value for an IN or OUT value within a stored procedure. Note
that this will only work if the IN or OUT value is a table-type
consisting of only one column of a basic type, for example \c{TYPE
myType IS TABLE OF VARCHAR(64) INDEX BY BINARY_INTEGER;}
\sa prepare(), bindValue(), addBindValue()
*/
bool QSqlQuery::execBatch(BatchExecutionMode mode)
{
return d->sqlResult->execBatch(mode == ValuesAsColumns);
}
/*!
Set the placeholder \a placeholder to be bound to value \a val in
the prepared statement. Note that the placeholder mark (e.g \c{:})
must be included when specifying the placeholder name. If \a
paramType is QSql::Out or QSql::InOut, the placeholder will be
overwritten with data from the database after the exec() call.
In this case, sufficient space must be pre-allocated to store
the result into.
To bind a NULL value, use a null QVariant; for example, use
\c {QVariant(QVariant::String)} if you are binding a string.
Values cannot be bound to multiple locations in the query, eg:
\code
INSERT INTO testtable (id, name, samename) VALUES (:id, :name, :name)
\endcode
Binding to name will bind to the first :name, but not the second.
\sa addBindValue(), prepare(), exec(), boundValue() boundValues()
*/
void QSqlQuery::bindValue(const QString& placeholder, const QVariant& val,
QSql::ParamType paramType
)
{
d->sqlResult->bindValue(placeholder, val, paramType);
}
/*!
Set the placeholder in position \a pos to be bound to value \a val
in the prepared statement. Field numbering starts at 0. If \a
paramType is QSql::Out or QSql::InOut, the placeholder will be
overwritten with data from the database after the exec() call.
*/
void QSqlQuery::bindValue(int pos, const QVariant& val, QSql::ParamType paramType)
{
d->sqlResult->bindValue(pos, val, paramType);
}
/*!
Adds the value \a val to the list of values when using positional
value binding. The order of the addBindValue() calls determines
which placeholder a value will be bound to in the prepared query.
If \a paramType is QSql::Out or QSql::InOut, the placeholder will be
overwritten with data from the database after the exec() call.
To bind a NULL value, use a null QVariant; for example, use \c
{QVariant(QVariant::String)} if you are binding a string.
\sa bindValue(), prepare(), exec(), boundValue() boundValues()
*/
void QSqlQuery::addBindValue(const QVariant& val, QSql::ParamType paramType)
{
d->sqlResult->addBindValue(val, paramType);
}
/*!
Returns the value for the \a placeholder.
\sa boundValues() bindValue() addBindValue()
*/
QVariant QSqlQuery::boundValue(const QString& placeholder) const
{
return d->sqlResult->boundValue(placeholder);
}
/*!
Returns the value for the placeholder at position \a pos.
*/
QVariant QSqlQuery::boundValue(int pos) const
{
return d->sqlResult->boundValue(pos);
}
/*!
Returns a map of the bound values.
With named binding, the bound values can be examined in the
following ways:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 14
With positional binding, the code becomes:
\snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 15
\sa boundValue() bindValue() addBindValue()
*/
QMap<QString,QVariant> QSqlQuery::boundValues() const
{
QMap<QString,QVariant> map;
const QVector<QVariant> values(d->sqlResult->boundValues());
for (int i = 0; i < values.count(); ++i)
map[d->sqlResult->boundValueName(i)] = values.at(i);
return map;
}
/*!
Returns the last query that was successfully executed.
In most cases this function returns the same string as lastQuery().
If a prepared query with placeholders is executed on a DBMS that
does not support it, the preparation of this query is emulated. The
placeholders in the original query are replaced with their bound
values to form a new query. This function returns the modified
query. It is mostly useful for debugging purposes.
\sa lastQuery()
*/
QString QSqlQuery::executedQuery() const
{
return d->sqlResult->executedQuery();
}
/*!
\fn bool QSqlQuery::prev()
Use previous() instead.
*/
/*!
Returns the object ID of the most recent inserted row if the
database supports it. An invalid QVariant will be returned if the
query did not insert any value or if the database does not report
the id back. If more than one row was touched by the insert, the
behavior is undefined.
For MySQL databases the row's auto-increment field will be returned.
\note For this function to work in PSQL, the table table must
contain OIDs, which may not have been created by default. Check the
\c default_with_oids configuration variable to be sure.
\sa QSqlDriver::hasFeature()
*/
QVariant QSqlQuery::lastInsertId() const
{
return d->sqlResult->lastInsertId();
}
/*!
Instruct the database driver to return numerical values with a
precision specified by \a precisionPolicy.
The Oracle driver, for example, can retrieve numerical values as
strings to prevent the loss of precision. If high precision doesn't
matter, use this method to increase execution speed by bypassing
string conversions.
Note: Drivers that don't support fetching numerical values with low
precision will ignore the precision policy. You can use
QSqlDriver::hasFeature() to find out whether a driver supports this
feature.
Note: Setting the precision policy doesn't affect the currently
active query. Call \l{exec()}{exec(QString)} or prepare() in order
to activate the policy.
\sa QSql::NumericalPrecisionPolicy, numericalPrecisionPolicy()
*/
void QSqlQuery::setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy precisionPolicy)
{
d->sqlResult->setNumericalPrecisionPolicy(precisionPolicy);
}
/*!
Returns the current precision policy.
\sa QSql::NumericalPrecisionPolicy, setNumericalPrecisionPolicy()
*/
QSql::NumericalPrecisionPolicy QSqlQuery::numericalPrecisionPolicy() const
{
return d->sqlResult->numericalPrecisionPolicy();
}
/*!
\since 4.3.2
Instruct the database driver that no more data will be fetched from
this query until it is re-executed. There is normally no need to
call this function, but it may be helpful in order to free resources
such as locks or cursors if you intend to re-use the query at a
later time.
Sets the query to inactive. Bound values retain their values.
\sa prepare() exec() isActive()
*/
void QSqlQuery::finish()
{
if (isActive()) {
d->sqlResult->setLastError(QSqlError());
d->sqlResult->setAt(QSql::BeforeFirstRow);
d->sqlResult->detachFromResultSet();
d->sqlResult->setActive(false);
}
}
/*!
\since 4.4
Discards the current result set and navigates to the next if available.
Some databases are capable of returning multiple result sets for
stored procedures or SQL batches (a query strings that contains
multiple statements). If multiple result sets are available after
executing a query this function can be used to navigate to the next
result set(s).
If a new result set is available this function will return true.
The query will be repositioned on an \e invalid record in the new
result set and must be navigated to a valid record before data
values can be retrieved. If a new result set isn't available the
function returns false and the query is set to inactive. In any
case the old result set will be discarded.
When one of the statements is a non-select statement a count of
affected rows may be available instead of a result set.
Note that some databases, i.e. Microsoft SQL Server, requires
non-scrollable cursors when working with multiple result sets. Some
databases may execute all statements at once while others may delay
the execution until the result set is actually accessed, and some
databases may have restrictions on which statements are allowed to
be used in a SQL batch.
\sa QSqlDriver::hasFeature() setForwardOnly() next() isSelect() numRowsAffected() isActive() lastError()
*/
bool QSqlQuery::nextResult()
{
if (isActive())
return d->sqlResult->nextResult();
return false;
}
QT_END_NAMESPACE