public bool Update(CRUD crud)
{
bool isSuccess = false;
SqlConnection conn = new SqlConnection(myconnstring);
try
{
string connect = null;
if (TrueOrFalse.Get() == true)
{
connect = "UPDATE Students SET LastName=@LastName,FirstName=@FirstName,Age=@Age WHERE StudentID=@ID ";
}
else
{
connect = "UPDATE Teachers SET LastName=@LastName,FirstName=@FirstName,Age=@Age WHERE TeacherID=@ID ";
}
string sql = connect +
"UPDATE Contacts SET City=@City,Address=@Address,Phone=@Phone WHERE ContactID=@ID";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.AddWithValue("@Id", crud.ID);
cmd.Parameters.AddWithValue("@LastName", crud.LastName);
cmd.Parameters.AddWithValue("@FirstName", crud.FirstName);
cmd.Parameters.AddWithValue("@Age", crud.Age);
cmd.Parameters.AddWithValue("@City", crud.City);
cmd.Parameters.AddWithValue("@Address", crud.Address);
cmd.Parameters.AddWithValue("@Phone", crud.Phone);
conn.Open();
int rows = cmd.ExecuteNonQuery();
if (rows > 0)
{
isSuccess = true;
}
else
{
isSuccess = false;
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
conn.Close();
}
return(isSuccess);
}
public bool Delete(CRUD crud)
{
bool isSuccess = false;
SqlConnection conn = new SqlConnection(myconnstring);
try
{
int currentnumber = ID - 1;
string lastarg = currentnumber.ToString() + " )";
string foo = "DBCC CHECKIDENT(Students, RESEED, " + lastarg;
string foo1 = "DBCC CHECKIDENT(Contacts, RESEED, " + lastarg;
if (TrueOrFalse.Get() == false)
{
foo = "DBCC CHECKIDENT(Teachers, RESEED, " + lastarg;
}
string connect = null;
if (TrueOrFalse.Get() == true)
{
connect = foo1 + "DELETE FROM Students WHERE StudentId=@Id " + foo;
}
else
{
connect = foo1 + "DELETE FROM Teachers WHERE TeacherID=@Id " + foo;
}
SqlCommand cmd = new SqlCommand(connect, conn);
cmd.Parameters.AddWithValue("@ID", crud.ID);
conn.Open();
int rows = cmd.ExecuteNonQuery();
if (rows > 0)
{
isSuccess = true;
}
else
{
isSuccess = false;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
conn.Close();
}
return(isSuccess);
}
public DataTable Select()
{
SqlConnection conn = new SqlConnection(myconnstring);
DataTable dt = new DataTable();
try
{
string sql = "SELECT s.StudentId,s.LastName,s.FirstName,s.Age,c.City,c.Address,c.Phone" +
" FROM Students as s LEFT JOIN Contacts as c ON s.StudentId=c.StudentId";
string sql1 = "SELECT s.TeacherID,s.LastName,s.FirstName,s.Age,c.City,c.Address,c.Phone" +
" FROM Teachers as s LEFT JOIN Contacts as c ON s.TeacherID=c.TeacherID";
string connect = null;
if (TrueOrFalse.Get() == true)
{
connect = sql;
}
else
{
connect = sql1;
}
SqlCommand cmd = new SqlCommand(connect, conn);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
conn.Open();
adapter.Fill(dt);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
conn.Close();
}
return(dt);
}
public bool Insert(CRUD crud)
{
bool isSuccess = false;
SqlConnection conn = new SqlConnection(myconnstring);
try
{
string teacher =
" INSERT INTO Teachers" +
"(LastName,FirstName,Age)" +
"VALUES" +
"(@LastName,@FirstName,@Age)";
string student =
" INSERT INTO Students" +
"(LastName,FirstName,Age)" +
"VALUES" +
"(@LastName,@FirstName,@Age)";
string contacts
= "INSERT INTO Contacts(StudentID,City,Address,Phone) " +
"VALUES (@ID,@City,@Address,@Phone)";
string contacts1
= "INSERT INTO Contacts(TeacherID,City,Address,Phone) " +
"VALUES (@ID,@City,@Address,@Phone)";
string connect = null;
if (TrueOrFalse.Get() == true)
{
connect = student + contacts;
}
else
{
connect = teacher + contacts1;
}
SqlCommand cmd = new SqlCommand(connect, conn);
cmd.Parameters.AddWithValue("@Id", crud.ID);
cmd.Parameters.AddWithValue("@FirstName", crud.FirstName);
cmd.Parameters.AddWithValue("@LastName", crud.LastName);
cmd.Parameters.AddWithValue("@Age", crud.Age);
cmd.Parameters.AddWithValue("@City", crud.City);
cmd.Parameters.AddWithValue("@Address", crud.Address);
cmd.Parameters.AddWithValue("@Phone", crud.Phone);
conn.Open();
int rows = cmd.ExecuteNonQuery();
if (rows > 0)
{
isSuccess = true;
}
else
{
isSuccess = false;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
conn.Close();
}
return(isSuccess);
}