gum::learning::DBInitializerFromSQL Class Reference

The class for initializing DatabaseTable and RawDatabaseTable instances from SQL databases. More...

#include <agrum/base/database/DBInitializerFromSQL.h>

Inheritance diagram for gum::learning::DBInitializerFromSQL:

Collaboration diagram for gum::learning::DBInitializerFromSQL:

Public Types
enum class	InputType : char { STRING , DBCELL }
	the enumeration indicating the type of the data the IDBInitializer expects as input data More...

Public Member Functions
Constructors / Destructors
	DBInitializerFromSQL (const std::string &dataSource, const std::string &login, const std::string &password, const std::string &query, long timeout=0L)
	default constructor, especially for postgresql databases
	DBInitializerFromSQL (const std::string &connection_string, const std::string &query, long timeout=0L)
	default constructor, especially for sqlite databases
	DBInitializerFromSQL (const DBInitializerFromSQL &from)
	copy constructor
	DBInitializerFromSQL (DBInitializerFromSQL &&from)
	move constructor
virtual DBInitializerFromSQL *	clone () const
	virtual copy constructor
virtual	~DBInitializerFromSQL ()
	destructor
Operators
DBInitializerFromSQL &	operator= (const DBInitializerFromSQL &from)
	copy operator
DBInitializerFromSQL &	operator= (DBInitializerFromSQL &&from)
	move operator
Accessors / Modifiers
const std::vector< std::string > &	variableNames ()
	returns the names of the variables in the input dataset
template<class DATABASE>
void	fillDatabase (DATABASE &database, const bool retry_insertion=false)
	fills the rows of the database table
std::size_t	throwingColumn () const
	This method indicates which column filling raised an exception, if any, during the execution of fillDatabase.

Protected Member Functions
virtual std::vector< std::string >	variableNames_ () final
	returns the names of the variables
virtual const std::vector< std::string > &	currentStringRow_ () final
	returns the content of the current row using strings
virtual bool	nextRow_ () final
	indicates whether there is a next row to read (and point on it)
virtual const DBRow< DBCell > &	currentDBCellRow_ ()
	asks the child class for the content of the current row using dbcells

Detailed Description

The class for initializing DatabaseTable and RawDatabaseTable instances from SQL databases.

In aGrUM, the usual way to create DatabaseTable instances used by learning algorithms is to use the 4-step process below:

1. Create an IDBInitializer instance (either a DBInitializerFromCSV or a DBInitializerFromSQL). This will enable to get the variables corresponding to the columns of the DatabaseTable.
2. Knowing these variables, create a DBTranslatorSet for encoding the lines of the CSV file or those of the SQL result into the appropriate values for the learning algorithms.
3. Create the DatabaseTable, passing it the DBTranslatorSet created in the preceding step. Use the IDBInitializer to provide the variables' names to the DatabaseTable.
4. Use the IDBInitializer to add the lines of the CSV file or those of the SQL result into the DatabaseTable.

The following codes show the details of this processe:

// 1/ use the initializer to parse all the columns/rows of a SQL result:
const std::string dataSource = "PostgreSQL";
const std::string login      = "gonzales";
const std::string password   = "agrum";
const std::string query      = "SELECT * FROM testunit.asia";
gum::learning::DBInitializerFromSQL
  initializer ( dataSource, login, password, query );
const auto& var_names = initializer.variableNames ();
const std::size_t nb_vars = var_names.size ();
 
// we create as many translators as there are variables
gum::learning::DBTranslator4LabelizedVariable translator;
gum::learning::DBTranslatorSet translator_set;
for ( std::size_t i = 0; i < nb_vars; ++i )
  translator_set.insertTranslator ( translator, i );
 
// create a DatabaseTable with these translators. For the moment, the
// DatabaseTable will be empty, i.e., it will contain no row
gum::learning::DatabaseTable database ( translator_set );
database.setVariableNames( initializer.variableNames () );
 
// use the DBInitializerFromSQL to fill the rows:
initializer.fillDatabase ( database );
// now, the database contains all the content of the ASIA database
 
 
// 2/ use an IDBInitializer to initialize a DatabaseTable, but ignore
// some columns.
gum::learning::DBInitializerFromSQL
  initializer2 ( dataSource, login, password, query );
gum::learning::DatabaseTable database2; // empty database
 
// indicate which columns of the SQL result should be read
database2.insertTranslator ( translator, 1 );
database2.insertTranslator ( translator, 3 );
database2.insertTranslator ( translator, 4 );
 
// sets the names of the columns correctly
database2.setVariableNames( initializer2.variableNames () );
 
// fill the rows:
initializer2.fillDatabase ( database2 );
// now all the rows of the SQL result have been transferred into
// database2, but only columns 1, 3 and 4 of the SQL result have
// been kept.
 
 
// 3/ another possibility to initialize a DatabaseTable, ignoring
// some columns:
gum::learning::DBInitializerFromSQL
  initializer3 ( dataSource, login, password, query );
gum::learning::DatabaseTable database3 ( translator_set );
// here, database3 is an empty database but it contains already
// translators for all the columns of the SQL result. We shall now
// remove the columns/translators that are not wanted anymore
database3.ignoreColumn ( 0 );
database3.ignoreColumn ( 2 );
database3.ignoreColumn ( 5 );
database3.ignoreColumn ( 6 );
database3.ignoreColumn ( 7 );
// asia contains 8 columns. The above ignoreColumns keep only columns
// 1, 3 and 4.
 
// sets the names of the columns correctly
database3.setVariableNames( initializer3.variableNames () );
// fill the rows:
initializer3.fillDatabase ( database3 );
// now all the rows of the SQL result have been transferred into
// database3, but only columns 1, 3 and 4 of the SQL result have
// been kept.

Definition at line 156 of file DBInitializerFromSQL.h.

Member Enumeration Documentation

InputType

enum class gum::learning::IDBInitializer::InputType : char

stronginherited

the enumeration indicating the type of the data the IDBInitializer expects as input data

Enumerator
STRING
DBCELL

Definition at line 139 of file IDBInitializer.h.

: char { STRING, DBCELL };

Constructor & Destructor Documentation

DBInitializerFromSQL() [1/4]

gum::learning::DBInitializerFromSQL::DBInitializerFromSQL	(	const std::string &	dataSource,
		const std::string &	login,
		const std::string &	password,
		const std::string &	query,
		long	timeout = 0L )

default constructor, especially for postgresql databases

This will read the result of query and load it in memory.

Parameters

dataSource	A declared dataSource in your odbc configuration file (usually /etc/odbc.ini).
login	The dataSource login.
password	The dataSource password.
query	The SQL query used as a database.
timeout	Defines a timeout for accessing the SQL database, if 0 then no timeout is set.

Referenced by DBInitializerFromSQL(), DBInitializerFromSQL(), clone(), operator=(), and operator=().

Here is the caller graph for this function:

DBInitializerFromSQL() [2/4]

gum::learning::DBInitializerFromSQL::DBInitializerFromSQL	(	const std::string &	connection_string,
		const std::string &	query,
		long	timeout = 0L )

default constructor, especially for sqlite databases

This will read the result of query and load it in memory.

Parameters

connection_string	a string specifying to nanODBC how to connect to a SQL database
query	The SQL query used as a database.
timeout	Defines a timeout for accessing the SQL database, if 0 then no timeout is set.

DBInitializerFromSQL() [3/4]

gum::learning::DBInitializerFromSQL::DBInitializerFromSQL

(

const DBInitializerFromSQL &

from

)

copy constructor

the new initializer points to the same SQL query as from, but it reparses the result it from scratch.

References DBInitializerFromSQL().

Here is the call graph for this function:

DBInitializerFromSQL() [4/4]

gum::learning::DBInitializerFromSQL::DBInitializerFromSQL

(

DBInitializerFromSQL &&

from

)

move constructor

References DBInitializerFromSQL().

Here is the call graph for this function:

~DBInitializerFromSQL()

virtual gum::learning::DBInitializerFromSQL::~DBInitializerFromSQL ( )

virtual

destructor

Member Function Documentation

clone()

virtual DBInitializerFromSQL * gum::learning::DBInitializerFromSQL::clone ( ) const

virtual

virtual copy constructor

Implements gum::learning::IDBInitializer.

References DBInitializerFromSQL().

Here is the call graph for this function:

currentDBCellRow_()

virtual const DBRow< DBCell > & gum::learning::IDBInitializer::currentDBCellRow_ ( )

protectedvirtualinherited

asks the child class for the content of the current row using dbcells

If the child class parses DBRows, this method should be overloaded

currentStringRow_()

virtual const std::vector< std::string > & gum::learning::DBInitializerFromSQL::currentStringRow_ ( )

finalprotectedvirtual

returns the content of the current row using strings

Reimplemented from gum::learning::IDBInitializer.

References currentStringRow_().

Referenced by currentStringRow_().

Here is the call graph for this function:

Here is the caller graph for this function:

fillDatabase()

template<class DATABASE>

void gum::learning::IDBInitializer::fillDatabase ( DATABASE & database, const bool retry_insertion = false )

inherited

fills the rows of the database table

This method may raise exceptions when trying to insert new rows into the database table. See Method insertRow() of the database table.

Referenced by gum::learning::IBNLearner::Database::Database(), gum::learning::IBNLearner::Database::Database(), gum::learning::readFile(), and gum::learning::IBNLearner::readFile_().

Here is the caller graph for this function:

nextRow_()

virtual bool gum::learning::DBInitializerFromSQL::nextRow_ ( )

finalprotectedvirtual

indicates whether there is a next row to read (and point on it)

Implements gum::learning::IDBInitializer.

References nextRow_().

Referenced by nextRow_().

Here is the call graph for this function:

Here is the caller graph for this function:

operator=() [1/2]

DBInitializerFromSQL & gum::learning::DBInitializerFromSQL::operator=

(

const DBInitializerFromSQL &

from

)

copy operator

the new initializer points to the same SQL query as from, but it reparses the result from scratch.

References DBInitializerFromSQL().

Here is the call graph for this function:

operator=() [2/2]

DBInitializerFromSQL & gum::learning::DBInitializerFromSQL::operator=

(

DBInitializerFromSQL &&

from

)

move operator

the new initializer points to the same SQL query as from, but it reparses the result from scratch.

References DBInitializerFromSQL().

Here is the call graph for this function:

throwingColumn()

std::size_t gum::learning::IDBInitializer::throwingColumn ( ) const

inherited

This method indicates which column filling raised an exception, if any, during the execution of fillDatabase.

variableNames()

const std::vector< std::string > & gum::learning::IDBInitializer::variableNames ( )

inherited

returns the names of the variables in the input dataset

Referenced by gum::learning::IBNLearner::Database::Database(), gum::learning::IBNLearner::Database::Database(), gum::learning::readFile(), and gum::learning::IBNLearner::readFile_().

Here is the caller graph for this function:

variableNames_()

virtual std::vector< std::string > gum::learning::DBInitializerFromSQL::variableNames_ ( )

finalprotectedvirtual

returns the names of the variables

Implements gum::learning::IDBInitializer.

---

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

• agrum/base/database/DBInitializerFromSQL.h