书籍源码

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Visual C++

StudentsPerClass.H：源码内容

							// StudentsPerClass.H : Declaration of the CStudentsPerClass class
#ifndef __STUDENTSPERCLASS_H_
#define __STUDENTSPERCLASS_H_
class CStudentsPerClassAccessor
{
public:
	TCHAR m_DepartmentName[51];
	TCHAR m_Description[51];
	LONG m_NumberOfStudents;
BEGIN_COLUMN_MAP(CStudentsPerClassAccessor)
	COLUMN_ENTRY(1, m_DepartmentName)
	COLUMN_ENTRY(2, m_Description)
	COLUMN_ENTRY(3, m_NumberOfStudents)
END_COLUMN_MAP()
DEFINE_COMMAND(CStudentsPerClassAccessor, _T(" 
	SELECT 
		DepartmentName, 
		Description, 
		Count(StudentID) AS NumberOfStudents 
	FROM (Department 
		INNER JOIN (Class 
				INNER JOIN Section 
					ON Class.ClassID = Section.ClassID) 
			ON Department.DepartmentCode 
				= Class.DepartmentCode) 
		LEFT JOIN StudentClass 
			ON Section.SectionID 
				= StudentClass.SectionID 
	GROUP BY DepartmentName, 
			 Description 
"))
	// You may wish to call this function if you are inserting a record and wish to
	// initialize all the fields, if you are not going to explicitly set all of them.
	void ClearRecord()
	{
		memset(this, 0, sizeof(*this));
	}
};
class CStudentsPerClass : public CCommand<CAccessor<CStudentsPerClassAccessor> >
{
public:
	HRESULT Open()
	{
		HRESULT		hr;
		hr = OpenDataSource();
		if (FAILED(hr))
			return hr;
		return OpenRowset();
	}
	HRESULT OpenDataSource()
	{
		HRESULT		hr;
		CDataSource db;
		CDBPropSet	dbinit(DBPROPSET_DBINIT);
		dbinit.AddProperty(DBPROP_AUTH_PERSIST_SENSITIVE_AUTHINFO, false);
		dbinit.AddProperty(DBPROP_INIT_DATASOURCE, OLESTR("Classes"));
		dbinit.AddProperty(DBPROP_INIT_PROMPT, (short)4);
		dbinit.AddProperty(DBPROP_INIT_LCID, (long)1033);
		hr = db.Open(_T("MSDASQL"), &dbinit);
		if (FAILED(hr))
			return hr;
		return m_session.Open(db);
	}
	HRESULT OpenRowset()
	{
		return CCommand<CAccessor<CStudentsPerClassAccessor> >::Open(m_session);
	}
	CSession	m_session;
};
#endif // __STUDENTSPERCLASS_H_

						