Dv::Sql::SelectExp Class Reference

This class represents a wrapper around a (reference-counted) pointer to a Dv::Sql::boolexp. More...

#include <select_exp.h>

Collaboration diagram for Dv::Sql::SelectExp:

Public Member Functions
	SelectExp (const boolexp *e)
	Constructor.
const boolexp &	exp () const
	Return underlying Dv::Sql::boolexp.
std::ostream &	print (std::ostream &os, const Dv::Sql::Db &db) const
	Print the expression in sql format.
const Dv::Sql::Table::Set &	tables () const
	The set of tables involved in this expression.
std::string	from () const
	Return "from" clause corresponding to this expression.
std::string	where (const Dv::Sql::Db &db) const
	Return where clause corresponding to this epression.
std::string	query (const Dv::Sql::Table::Ref &table, const std::string &rest="") const
	Return a complete select statement corresponding to this expression and a table.
std::string	from_where (Dv::Sql::Db &db, const std::string &rest="") const
	Return "from .. where .. " part of an sql select statement corresponding to this expression.
Static Public Member Functions
static SelectExp	true_exp ()
	Return "true" SelectExp.
Private Attributes
Dv::shared_ptr< const boolexp >	exp_

Detailed Description

This class represents a wrapper around a (reference-counted) pointer to a Dv::Sql::boolexp.

Example

 Dv::Sql::Table::Column col1;
 Dv::Sql::Table::Column col2;
 int i;
 std::string s;
 Dv::Sql::SelectExp exp( col1 > i && col2 == s );

Definition at line 356 of file select_exp.h.

Constructor & Destructor Documentation

Dv::Sql::SelectExp::SelectExp ( const boolexp * e ) [inline]

Constructor.

It simply wraps a (reference-counted) pointer to an expression.

Parameters:

e

pointer to expression to be wrapped

Definition at line 362 of file select_exp.h.

Member Function Documentation

const boolexp& Dv::Sql::SelectExp::exp ( ) const [inline]

Return underlying Dv::Sql::boolexp.

Returns:: underlying Dv::Sql::boolexp.

Definition at line 367 of file select_exp.h.

References exp_.

Referenced by Dv::Sql::complex_boolexp::complex_boolexp().

std::ostream& Dv::Sql::SelectExp::print	(	std::ostream &	os,
		const Dv::Sql::Db &	db
	)			const

Print the expression in sql format.

Parameters:

	os	stream to print on
	db	to use for escaping string values

Returns:: os

const Dv::Sql::Table::Set& Dv::Sql::SelectExp::tables ( ) const [inline]

The set of tables involved in this expression.

Returns:: the set of tables involved in this expression

See also:: Dv::Sql::boolexp::tables

Definition at line 379 of file select_exp.h.

References exp_.

std::string Dv::Sql::SelectExp::from ( ) const [inline]

Return "from" clause corresponding to this expression.

Returns:

A string of the form

  from table_1 , table_2 , .. , table_n

where "from" is preceeded by a space and table_1, .. , table_n are the names of the tables mentioned in the expression.

See also:: Dv::Sql::boolexp::tables; Dv::Sql::boolexp::from

Definition at line 391 of file select_exp.h.

References exp_.

std::string Dv::Sql::SelectExp::where ( const Dv::Sql::Db & db ) const [inline]

Return where clause corresponding to this epression.

Parameters:

db

database connection (needed for DBMS-dependent escape for string values).

Returns:

a string of the form

  where condition

where "where" is preceeded by a space and condition is generated by Dv::Sql::boolexp::print.

See also:: Dv::Sql::boolexp::where

Definition at line 403 of file select_exp.h.

References exp_.

std::string Dv::Sql::SelectExp::query	(	const Dv::Sql::Table::Ref &	table,
		const std::string &	rest = `""`
	)			const `[inline]`

Return a complete select statement corresponding to this expression and a table.

The statement retrieves all columns (using "select distinct") of the table.

Parameters:

	table	for which the columns need to be retrieved
	rest	optional suffix for the statement.

Returns:

a full sql select statement of the form

 table->select(true) +  from() + where(table->db()) + rest

See also:: Dv::Sql::Table::select; Dv::Sql::SelectExp::from

Definition at line 417 of file select_exp.h.

References exp_.

std::string Dv::Sql::SelectExp::from_where	(	Dv::Sql::Db &	db,
		const std::string &	rest = `""`
	)			const `[inline]`

Return "from .. where .. " part of an sql select statement corresponding to this expression.

Parameters:

	db	database connection (needed for DBMS-dependent escape for string values).
	rest	optional suffix to append to the generated string.

Returns:

the string

 from() + where() + rest

Example

 Customer::Row cust;
 ...
 Dv::Sql::SelectExp e = acct_cust.match_target(cust) 
                        && acct_cust.match() 
                        && trans_acct.match();
 Dv::Sql::Object total(db, 
              "select sum(transaction.amount) as total" + e.from_where(db));