Dv::Sql::Row< database_table > Class Template Reference

A class template of which each instantiation class represents the rows of a relational table. More...

#include <row.h>

Inheritance diagram for Dv::Sql::Row< database_table >:

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Collaboration diagram for Dv::Sql::Row< database_table >:

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List of all members.

Classes
struct	Column
	A Row<T>::Column object should be considered as a reference to a Table::Column object. More...
class	Set
	A set of rows of this table. More...
Public Member Functions
	Row ()
	An empty row.
	Row (SelectExp select_exp, const std::string &rest="") throw (std::logic_error, std::runtime_error)
	Initialize a row object with data matching the first result in an SQL select statement defined by select_exp followed by rest.
	Row (Dv::Sql::Command &q, unsigned int r) throw (std::logic_error, std::runtime_error)
	Initialize a row object with data from the r'th row in the answer of a query q.
	Row (const Dv::Sql::Object &source, const Dv::Sql::Reference &reference) throw (std::runtime_error, std::logic_error)
	Initialize a row using data from a row that is obtained by "following a reference".
bool	is_null (const Column &column) const
	Is the column value null?
template<typename T >
T	operator() (const Column &column, const T &default_value) const
	Obtain column value for a row.
Static Public Member Functions
static Dv::Sql::Table::Ref	table ()
static Dv::Sql::Db &	db ()
static void	erase_all (SelectExp select_exp)

Detailed Description

template<Dv::Sql::Table::Ref & database_table>
class Dv::Sql::Row< database_table >

A class template of which each instantiation class represents the rows of a relational table.

The template parameter is a (reference to) a Dv::Sql::Table object, for which the class instances represent rows. A Row object is essentially a Dv::Sql::Object with a fixed associated database table (note that the association between an object and a database table cannot be changed: see Dv::Sql::Object::set_table).

See also:: Dv::Sql::Table; Dv::Sql::Object

Examples:: example-database.C, and example-row.C.

Definition at line 25 of file row.h.

Constructor & Destructor Documentation

template<Dv::Sql::Table::Ref & database_table>

Dv::Sql::Row< database_table >::Row ( ) [inline]

An empty row.

See also:: Dv::Sql::Object::Object(Dv::Sql::Table::Ref)

Definition at line 34 of file row.h.

template<Dv::Sql::Table::Ref & database_table>

Dv::Sql::Row< database_table >::Row	(	SelectExp	select_exp,
		const std::string &	rest = `""`
	)			throw (std::logic_error, std::runtime_error) `[inline]`

Initialize a row object with data matching the first result in an SQL select statement defined by select_exp followed by rest.

Example:

 std::string n("Jones"0;
 Row<customer> customer(name == n, "order by age");

will retrieve the youngest customer called "Jones".

Parameters:

	select_exp	boolean condition that is translated to the "where" clause in the SQL select statement.
	rest	optional part of the SQL select statement follwing the "where" clause.

Exceptions:

	std::runtime_error	if the query returns no anwers
	std::logic_error	if the query caused an SQL error

Definition at line 55 of file row.h.

template<Dv::Sql::Table::Ref & database_table>

Dv::Sql::Row< database_table >::Row	(	Dv::Sql::Command &	q,
		unsigned int	r
	)			throw (std::logic_error, std::runtime_error) `[inline]`

Initialize a row object with data from the r'th row in the answer of a query q.

Example

 Db::Sql::Command q(db, "select * from customer where",
    age < 21 && name ^ "A%", "order by age");
 Row<customer> customer(q, 2);

Parameters:

	q	the query for which the answer will supply the data to initialize the row object
	r	the number of the row in the query answer from which the data will be used to initialize this row object.

Exceptions:

	std::runtime_error	if the query returns less than r answers
	std::logic_error	if the query caused an SQL error or if the number of columns in the query answer is not equal to the number of columns in table_ref (the template parameter).

Definition at line 78 of file row.h.

template<Dv::Sql::Table::Ref & database_table>

Dv::Sql::Row< database_table >::Row	(	const Dv::Sql::Object &	source,
		const Dv::Sql::Reference &	reference
	)			throw (std::runtime_error, std::logic_error) `[inline]`

Initialize a row using data from a row that is obtained by "following a reference".

The data are obtained from the first row of the result of a query that selects the rows of the target table that match data from the source object in the colums indicated by the reference object.

Example

 // Define reference from account(customer_id) to customer(id)
 const Dv::Sql::Reference acct_cust(
           Database::account, (cols = &Account::customer_id), 
           Database::customer, (cols = &Customer::id)
           );
 Row<account> acct;
 // Cust will be initialized using data from the first
 // (only) customer with id acct.cust_id
 Row<customer> cust(acct, acct_cust);

Parameters:

	source	object from which the reference will be followed. It should be a row from reference.from_table.
	reference	that will be followed. Its to_table should match database_table (the template parameter) of this object.

Exceptions:

	std::runtime_error	if the resulting query returns no answers
	std::logic_error	if the query caused an SQL error or if the number of columns in the query answer is not equal to the number of columns in table_ref (the template parameter) or if the number of columns in the source object does not equal the number of columns in reference.from_table.

Definition at line 113 of file row.h.

Member Function Documentation

template<Dv::Sql::Table::Ref & database_table>

static Dv::Sql::Table::Ref Dv::Sql::Row< database_table >::table ( ) [inline, static]

Definition at line 28 of file row.h.

Referenced by Dv::Sql::Row< database_table >::erase_all().

template<Dv::Sql::Table::Ref & database_table>

static Dv::Sql::Db& Dv::Sql::Row< database_table >::db ( ) [inline, static]

Definition at line 29 of file row.h.

Referenced by Dv::Sql::Row< database_table >::erase_all().

template<Dv::Sql::Table::Ref & database_table>

static void Dv::Sql::Row< database_table >::erase_all ( SelectExp select_exp ) [inline, static]

Definition at line 117 of file row.h.

References Dv::Sql::Row< database_table >::db(), and Dv::Sql::Row< database_table >::table().

template<Dv::Sql::Table::Ref & database_table>

bool Dv::Sql::Row< database_table >::is_null ( const Column & column ) const [inline]

Is the column value null?

Parameters:

column

as generated by db2cpp

Returns:: true iff the column value is null

Definition at line 166 of file row.h.

References Dv::Sql::Column::index().

template<Dv::Sql::Table::Ref & database_table>

template<typename T >

T Dv::Sql::Row< database_table >::operator()	(	const Column &	column,
		const T &	default_value
	)			const `[inline]`

Obtain column value for a row.

Parameters:

	column	as generated by db2cpp
	default_value	returned if the 'real' value of the column is null, should enable automatic deduction of T

Returns:: the value of the column for this row

Definition at line 177 of file row.h.

References Dv::Sql::Column::index().

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

row.h

Dv::Sql::Row< database_table > Class Template Reference

Classes

Public Member Functions

Static Public Member Functions

Detailed Description

template<Dv::Sql::Table::Ref & database_table> class Dv::Sql::Row< database_table >

Constructor & Destructor Documentation

Member Function Documentation

template<Dv::Sql::Table::Ref & database_table>
class Dv::Sql::Row< database_table >