Question

我想删除数据网格中以及数据库中的多行，但是我什至在删除数据网格中的多行时也遇到问题... 我可以用我的代码删除一行（仅从datagrid中删除），但这还不够。

我正在尝试使用它：

var grid = StudentsDataGrid;
var mygrid = StudentsDataGrid;

        if (grid.SelectedIndex >= 0)
        {
            for (int i = grid.SelectedItems.Count -1; i >= 0; i--)
            {
                mygrid.Items.Remove(grid.SelectedItems[i]);
            };
        }

        grid = mygrid;

但是我收到一条错误消息，指出使用ItemsSource时操作不正确。而是使用对元素的访问权限，并通过ItemsControl.ItemsSource对其进行更改。

我的方法仅适用于一行：

private void RemoveButton_Click(object sender, EventArgs e){
         Student student = StudentsDataGrid.SelectedItem as Student;
         StudentsList.Remove(student);
}

也许我应该更改将数据库链接到datagrid的方式。这是我读取数据库的部分

OpenConection();
using (SqlDataReader dr = DataReader("SELECT IdStudent, FirstName, LastName, Address, IndexNumber, Name FROM apbd.Student INNER JOIN apbd.Studies ON Student.IdStudies = Studies.IdStudies"))
                {
                    list = new ObservableCollection<Student>();
                    while (dr.Read())
                    {
                        string idstudent = dr["IdStudent"].ToString();
                        string firstname = dr["FirstName"].ToString();
                        string lastname = dr["LastName"].ToString();
                        string address = dr["Address"].ToString();
                        string index = dr["IndexNumber"].ToString();
                        string studies = dr["Name"].ToString();

                        if (dr["IdStudent"] != DBNull.Value)
                        {
                            int? emp = (int?)dr["IdStudent"];
                        }

                    list.Add(new Student
                    {
                            IdStudent = idstudent,
                            Imie = firstname,
                            Nazwisko = lastname,
                            Adres = address,
                            Index = index,
                            Studia = studies,                       
                        });

                    }
                }
            CloseConnection();
            return list;
        }

在主类中，我通过ItemsSource将其链接到DataGrid：

public void LoadDataToDataGrid()
        {
            StudentsList = new ObservableCollection<Student>();

            var instance = new StudentsDbService();
            StudentsList = instance.ShowData();
            StudentsDataGrid.ItemsSource = StudentsList;

        }

好吧，我想我已经找到一种删除datagrid中多行的方法：

private void RemoveButton_Click(object sender, EventArgs e)
        {
            ObservableCollection<Student> itemsToRemove = new ObservableCollection<Student>();

            foreach (Student item in StudentsDataGrid.SelectedItems)
            {
                itemsToRemove.Add(item);
            }
            foreach (Student item in itemsToRemove)
            {
                ((ObservableCollection<Student>)StudentsDataGrid.ItemsSource).Remove(item);
            }
        }

但是现在如何从数据库中删除特定记录？我是否应该将以前通过的IdStudent作为学生对象中的值之一传递？

猜猜我找到了一种方法，但是请告诉我它有多糟？

这是修改后的部分，负责从DataGrid中删除记录：

private void RemoveButton_Click(object sender, EventArgs e)
        {
            ObservableCollection<Student> itemsToRemove = new ObservableCollection<Student>();
            List<string> studentID = new List<string>();

            foreach (Student item in StudentsDataGrid.SelectedItems)
            {
                itemsToRemove.Add(item);
                studentID.Add(item.IdStudent);
            }
            foreach (Student item in itemsToRemove)
            {
                ((ObservableCollection<Student>)StudentsDataGrid.ItemsSource).Remove(item);
            }
            var instance = new StudentsDbService();
            instance.deleteRecords(studentID);
        }

这是我从数据库中删除记录的部分：

public void deleteRecords(List<string> studentID)
        {
            OpenConection();
            foreach (string item in studentID)
            {
                ExecuteQueries("DELETE FROM apbd.Student WHERE IdStudent=" + item);
            }

            CloseConnection();
        }

如何删除数据网格和数据库中的多行？

0 个答案: