KDbPreparedStatement Class Reference

#include <KDbPreparedStatement.h>

Inheritance diagram for KDbPreparedStatement:

Classes
class	Data

Public Types
enum	Type { InvalidStatement , SelectStatement , InsertStatement }

Public Member Functions
	KDbPreparedStatement ()
bool	execute (const KDbPreparedStatementParameters &parameters)
const KDbFieldList *	fields () const
bool	isValid () const
quint64	lastInsertRecordId () const
void	setFields (KDbFieldList *fields)
void	setType (KDbPreparedStatement::Type type)
void	setWhereFieldNames (const QStringList &whereFieldNames)
KDbPreparedStatement::Type	type () const
QStringList	whereFieldNames () const
Public Member Functions inherited from KDbResultable
	KDbResultable (const KDbResultable &other)
void	clearResult ()
KDbMessageHandler *	messageHandler () const
KDbResultable &	operator= (const KDbResultable &other)
KDbResult	result () const
virtual QString	serverResultName () const
void	setMessageHandler (KDbMessageHandler *handler)
void	showMessage ()

Protected Member Functions
	KDbPreparedStatement (KDbPreparedStatementInterface *iface, Type type, KDbFieldList *fields, const QStringList &whereFieldNames=QStringList())

Additional Inherited Members
Protected Attributes inherited from KDbResultable
Private *const	d
KDbResult	m_result

Detailed Description

Prepared database command for optimizing sequences of multiple database actions.

Currently INSERT and SELECT statements are supported. For example when using KDbPreparedStatement for INSERTs, you can gain about 30% speedup compared to using multiple connection.insertRecord(*tabelSchema, dbRecordBuffer).

To use KDbPreparedStatement, create is using KDbConnection:prepareStatement(), providing table schema; set up parameters using operator << ( const QVariant& value ); and call execute() when ready. KDbPreparedStatement objects are accessed using KDE shared pointers, i.e KDbPreparedStatement, so you do not need to remember about destroying them. However, when underlying KDbConnection object is destroyed, KDbPreparedStatement should not be used.

Let's assume tableSchema contains two columns NUMBER integer and TEXT text. Following code inserts 10000 records with random numbers and text strings obtained elsewhere using getText(i).

bool insertMultiple(KDbConnection* conn, KDbTableSchema* tableSchema)
{
  KDbPreparedStatement statement = conn->prepareStatement(
    KDbPreparedStatement::Insert, tableSchema);
  for (i=0; i<10000; i++) {
    KDbPreparedStatementParameters parameters;
    parameters << qrand() << getText(i);
    if (!statement.execute(parameters))
      return false;
  }
  return true;
}

If you do not call clearParameters() after every insert, you can insert the same value multiple times using execute() what increases efficiency even more.

Another use case is inserting large objects (BLOBs or CLOBs). Depending on database backend, you can avoid escaping BLOBs. See KexiFormView::storeData() for example use.

Definition at line 75 of file KDbPreparedStatement.h.

Member Enumeration Documentation

Type

enum KDbPreparedStatement::Type

Defines type of the prepared statement.

Enumerator
InvalidStatement	Used only in invalid statements.
SelectStatement	SELECT statement will be prepared end executed.
InsertStatement	INSERT statement will be prepared end executed.

Definition at line 80 of file KDbPreparedStatement.h.

Constructor & Destructor Documentation

KDbPreparedStatement() [1/2]

KDbPreparedStatement::KDbPreparedStatement

(

)

Creates an invalid prepared statement.

Definition at line 46 of file KDbPreparedStatement.cpp.

~KDbPreparedStatement()

KDbPreparedStatement::~KDbPreparedStatement ( )

override

Definition at line 58 of file KDbPreparedStatement.cpp.

KDbPreparedStatement() [2/2]

KDbPreparedStatement::KDbPreparedStatement ( KDbPreparedStatementInterface * iface, Type type, KDbFieldList * fields, const QStringList & whereFieldNames = QStringList() )

protected

Creates a new prepared statement.

In your code use Users call KDbConnection:prepareStatement() instead.

Definition at line 51 of file KDbPreparedStatement.cpp.

Member Function Documentation

execute()

bool KDbPreparedStatement::execute

(

const KDbPreparedStatementParameters &

parameters

)

Executes the prepared statement using parameters parameters. A number parameters set up for the statement must be the same as a number of fields defined in the underlying database table.

Returns

false on failure. Detailed error status can be obtained from KDbConnection object that was used to create this statement object.

Todo

error message?

Definition at line 62 of file KDbPreparedStatement.cpp.

fields()

const KDbFieldList * KDbPreparedStatement::fields

(

)

const

Definition at line 189 of file KDbPreparedStatement.cpp.

isValid()

bool KDbPreparedStatement::isValid

(

)

const

Definition at line 173 of file KDbPreparedStatement.cpp.

lastInsertRecordId()

quint64 KDbPreparedStatement::lastInsertRecordId

(

)

const

Returns

unique identifier of the most recently inserted record. Typically this is just primary key value. This identifier could be reused when we want to reference just inserted record. If there was no insertion recently performed, std::numeric_limits<quint64>::max() is returned.

Definition at line 213 of file KDbPreparedStatement.cpp.

setFields()

void KDbPreparedStatement::setFields

(

KDbFieldList *

fields

)

Sets fields for the statement. Does nothing if fields is nullptr.

Definition at line 194 of file KDbPreparedStatement.cpp.

setType()

void KDbPreparedStatement::setType

(

KDbPreparedStatement::Type

type

)

Definition at line 183 of file KDbPreparedStatement.cpp.

setWhereFieldNames()

void KDbPreparedStatement::setWhereFieldNames

(

const QStringList &

whereFieldNames

)

Definition at line 207 of file KDbPreparedStatement.cpp.

type()

KDbPreparedStatement::Type KDbPreparedStatement::type

(

)

const

Definition at line 178 of file KDbPreparedStatement.cpp.

whereFieldNames()

QStringList KDbPreparedStatement::whereFieldNames

(

)

const

Definition at line 202 of file KDbPreparedStatement.cpp.

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The documentation for this class was generated from the following files:

• KDbPreparedStatement.h
• KDbPreparedStatement.cpp