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Описание контрольного примера
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В качестве контрольного примера рассмотрим выполнение запроса на подсчет кол-ва тестов за определенный промежуток времени
1.Входим в систему
2.Выбираем пункт меню «запросы»
3.Выбирем нужный нам запрос
4.Вводим данные и нажимаем «ок»
5.Вводим другой промежуток времени
Сообщения программы, причины, их вызывающие, и реакция пользователя на сообщения
1.Сообщение о неверном вводе логина или пароля
2.Попытка создания записи главного администратора
В системе запрещено создание дублирующих записей. Запись главного администратора является единственной и не может быть удалена из системы.
Текст программы, с необходимыми комментариями
Реализация входа пользователя в систему
private: System::Void Вход_Click(System::Object^ sender, System::EventArgs^ e) {
if((textBox1->Text!="") && (textBox2->Text!=""))
{
String^ connect="provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection = gcnew OleDbConnection(connect);
OleDbCommand^ myOleDbCommand = myOleDbConnection->CreateCommand();
myOleDbCommand->CommandText =
"Select [id],[lvl]"+
"FROM [auth]"+
"WHERE [login]='"+textBox1->Text+"' AND ([pass]='"+textBox2->Text+"');";
myOleDbConnection->Open();
OleDbDataReader^ myOleDbDataReader = myOleDbCommand->ExecuteReader();
while(myOleDbDataReader->Read())
{
id=Convert::ToInt32(myOleDbDataReader[0]);
lvl=Convert::ToInt32(myOleDbDataReader[1]);
}
myOleDbDataReader->Close();
myOleDbConnection->Close();
}
else
{
this->label3->Visible=true;
}
if(lvl==0)
{
String^ connectionString2 = "provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection2 = gcnew OleDbConnection(connectionString2);
OleDbCommand^ myOleDbCommand2 = myOleDbConnection2->CreateCommand();
myOleDbCommand2->CommandText =
"INSERT INTO [log] "+
"VALUES ("+id+", Now(), 'Вход в систему');";
myOleDbConnection2->Open();
OleDbDataReader^ myOleDbDataReader2 = myOleDbCommand2->ExecuteReader();
myOleDbConnection2->Close();
this->Text = L"Работа с БД";
this->ClientSize = System::Drawing::Size(500, 220);
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this->menuStrip1->Visible=true;
this->textBox1->Visible=false;
this->textBox2->Visible=false;
this->label1->Visible=false;
this->label2->Visible=false;
this->Вход->Visible=false;
this->Выход->Visible=false;
this->dataGridView1->Visible=true;
this->dataGridView1->Location = System::Drawing::Point(12,30);
this->listBox1->Visible=true;
this->listBox1->Location=System::Drawing::Point(300,30);
}
if(lvl==1)
{
String^ connectionString2 = "provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection2 = gcnew OleDbConnection(connectionString2);
OleDbCommand^ myOleDbCommand2 = myOleDbConnection2->CreateCommand();
myOleDbCommand2->CommandText =
"INSERT INTO [log] "+
"VALUES ("+id+", Now(), 'Вход в систему');";
myOleDbConnection2->Open();
OleDbDataReader^ myOleDbDataReader2 = myOleDbCommand2->ExecuteReader();
myOleDbConnection2->Close();
this->Text = L"Работа с БД";
this->ClientSize = System::Drawing::Size(500, 220);
this->menuStrip1->Visible=true;
this->пользователяToolStripMenuItem->Visible=false;
this->участникиToolStripMenuItem->Visible=false;
this->логToolStripMenuItem->Visible=false;
this->textBox1->Visible=false;
this->textBox2->Visible=false;
this->label1->Visible=false;
this->label2->Visible=false;
this->Вход->Visible=false;
this->Выход->Visible=false;
this->dataGridView1->Visible=true;
this->dataGridView1->Location = System::Drawing::Point(12,30);
this->dataGridView1->ReadOnly=false;
this->listBox1->Visible=true;
this->listBox1->Location=System::Drawing::Point(300,30);
this->Сохранить->Enabled=true;
}
if(lvl==2)
{
String^ connectionString2 = "provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection2 = gcnew OleDbConnection(connectionString2);
OleDbCommand^ myOleDbCommand2 = myOleDbConnection2->CreateCommand();
myOleDbCommand2->CommandText =
"INSERT INTO [log] "+
"VALUES ("+id+", Now(), 'Вход в систему');";
myOleDbConnection2->Open();
OleDbDataReader^ myOleDbDataReader2 = myOleDbCommand2->ExecuteReader();
myOleDbConnection2->Close();
this->Text = L"Работа с БД";
this->ClientSize = System::Drawing::Size(500, 220);
this->menuStrip1->Visible=true;
this->пользователяToolStripMenuItem->Visible=false;
this->тестВопросToolStripMenuItem->Visible=false;
this->вопросОтветToolStripMenuItem->Visible=false;
this->ответыToolStripMenuItem->Visible=false;
this->участникиToolStripMenuItem->Visible=false;
this->тестыToolStripMenuItem->Visible=false;
this->логToolStripMenuItem->Visible=false;
this->уровеньToolStripMenuItem->Visible=false;
this->textBox1->Visible=false;
this->textBox2->Visible=false;
this->label1->Visible=false;
this->label2->Visible=false;
this->Вход->Visible=false;
this->Выход->Visible=false;
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this->dataGridView1->Visible=true;
this->dataGridView1->Location = System::Drawing::Point(12,30);
this->dataGridView1->ReadOnly=true;
this->listBox1->Visible=true;
this->listBox1->Location=System::Drawing::Point(300,30);
this->Сохранить->Enabled=false;
}
}
Участок кода, реализующий один из запросов
if (flag==7)
{
String^ connect="provider=Microsoft.Jet.OLEDB.4.0;"+path_d;
OleDbConnection^ myOleDbConnection = gcnew OleDbConnection(connect);
DataSet = gcnew System::Data::DataSet();
DataSet->CaseSensitive = true;
OleDbCommand^ myOleDbCommand = myOleDbConnection->CreateCommand();
myOleDbCommand->CommandText ="SELECT Answer.grade, Test_Question.ID_test, Test_Question.ID_question, Answer.ID_answer FROM Answer INNER JOIN (Test_Question INNER JOIN Answer_Question ON Test_Question.ID_question = Answer_Question.ID_question) ON Answer.ID_answer = Answer_Question.ID_answer WHERE (((Test_Question.ID_test)='"+this->textBox3->Text+"') AND ((Test_Question.ID_question)=[Answer_Question].[ID_question]) AND ((Answer.ID_answer)=[Answer_Question].[ID_answer]) AND ((Answer.correct)='yes'));";
myOleDbConnection->Open();
myOleDbDataAdapter = gcnew OleDbDataAdapter();
myOleDbDataAdapter->SelectCommand = myOleDbCommand;
myOleDbDataAdapter->Fill(DataSet,"Test");
dataGridView1->DataSource = DataSet;
dataGridView1->DataMember = "Test";
this->dataGridView1->DataSource = DataSet->Tables["Test"]->DefaultView;
myOleDbConnection->Close();
table="Test";
String^ connectionString2 = "provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection2 = gcnew OleDbConnection(connectionString2);
OleDbCommand^ myOleDbCommand2 = myOleDbConnection2->CreateCommand();
myOleDbCommand2->CommandText =
"INSERT INTO [log] "+
"VALUES ("+id+", Now(), 'Вывод оценок теста с указанием id теста');";
myOleDbConnection2->Open();
OleDbDataReader^ myOleDbDataReader2 = myOleDbCommand2->ExecuteReader();
myOleDbConnection2->Close();
}
Так как изменение данных и создание новой записи происходят средствами компонента datagridview то далее будет показан код, отвечающий за сохранение этих данных (кнопка «сохранить»)
private: System::Void Сохранить_Click(System::Object^ sender, System::EventArgs^ e) {
OleDbCommandBuilder^ myOleDbCommandBuilder=gcnew OleDbCommandBuilder(myOleDbDataAdapter);
myOleDbDataAdapter->Update(DataSet,table);
DataSet->AcceptChanges();
String^ connectionString2 = "provider=Microsoft.Jet.OLEDB.4.0;"+path_a;
OleDbConnection^ myOleDbConnection2 = gcnew OleDbConnection(connectionString2);
OleDbCommand^ myOleDbCommand2 = myOleDbConnection2->CreateCommand();
myOleDbCommand2->CommandText =
"INSERT INTO [log] "+
"VALUES ("+id+", Now(), 'Сохранение изменений');";
myOleDbConnection2->Open();
OleDbDataReader^ myOleDbDataReader2 = myOleDbCommand2->ExecuteReader();
myOleDbConnection2->Close();
}
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