// SelectQuery.h 

#ifndef dset__SelectQuery_H
#define dset__SelectQuery_H

// Chitra Kannan
// July 2004
//
// Class to build a Sql Select Query. It is intended to carry the fields/columns
// and the constraint: not the from clause.

#include <string>
#include <vector>
#include <iosfwd>

namespace dset {

class SelectQuery {

public:  // tyepdefs

  typedef std::string Constraint;

private: //Data Members

  std::string m_columns;	// 'select' clause as a string
  Constraint m_constraint; 	// 'where' clause
  bool m_validity;		

public:  // methods

  // Default constructor.
  explicit SelectQuery(std::string columns ="", std::string condition ="");

  // Destructor.
  virtual ~SelectQuery();

  // Reset the sql query,i.e, set m_onstraint to null
  SelectQuery& reset();
 
  // Is the sql query valid
  bool is_valid() const;

  // Set a sql query.
  SelectQuery& set(std::string columns, Constraint con);

  // Add AND constraint to sql query.
  SelectQuery& andconstraint(Constraint con);

  // Add OR constraint to sql query.
  SelectQuery& orconstraint(Constraint con);
  
  // Get constraint on the current sql query.
  std::string get_constraint() const;

  // Get current sql query.
  std::string get_columns() const;

};

}  // end dataset namespace

// Output stream.
std::ostream& operator<< (std::ostream& lhs, const dset::SelectQuery& rhs);

#endif