Windows Form ตอนที่ 6 : Delete Data (LINQ, Entity Framework)

    public partial class frmMain : Form
    {
        public frmMain()
        {
            InitializeComponent();
        }

        private void frmMain_Load(object sender, EventArgs e)
        {
            BindData();
        }

        private void BindData()
        {
            // Create new entities Object
            using (var db = new myDatabaseEntities())
            {

                // Get data from CUSTOMER
                var ds = (from c in db.CUSTOMER
                          select new
                          {
                              c.CUSTOMER_ID,
                              c.NAME,
                              c.EMAIL,
                              c.COUNTRY_CODE,
                              c.BUDGET,
                              c.USED
                          }).ToList();

                // Assign to DataGridView
                if (ds.Count > 0)
                {
                    // New DataSource
                    this.myDataGridView.AutoGenerateColumns = false;
                    this.myDataGridView.AllowUserToAddRows = false;
                    this.myDataGridView.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
                    this.myDataGridView.DataSource = ds;
                }

                // Summary Budget Column
                decimal iSumBudget = 0;
                foreach (DataGridViewRow row in this.myDataGridView.Rows)
                {
                    iSumBudget = iSumBudget + Convert.ToDecimal(row.Cells["BUDGET"].Value);
                }
                this.lblTotalBudget.Text = String.Format("Total Budget : {0}", iSumBudget.ToString("#,###.00"));

                // Summary Used Column
                decimal iSumUsed = 0;
                foreach (DataGridViewRow row in this.myDataGridView.Rows)
                {
                    iSumUsed = iSumUsed + Convert.ToDecimal(row.Cells["USED"].Value);
                }
                this.lblTotalUsed.Text = String.Format("Total Used : {0}", iSumUsed.ToString("#,###.00"));

            }
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            string strCustomerID = this.myDataGridView.Rows[this.myDataGridView.CurrentCell.RowIndex].Cells["CUSTOMER_ID"].Value.ToString();

            if (MessageBox.Show(string.Format("Are you sure to delete {0}?", strCustomerID), "Confirm.",
                MessageBoxButtons.YesNo, MessageBoxIcon.Question,
                MessageBoxDefaultButton.Button1) == DialogResult.Yes)
            {

                // Create new entities from Entities
                using (var db = new myDatabaseEntities())
                {
                    // Delete CUSTOMER
                    var del = (from c in db.CUSTOMER
                               where c.CUSTOMER_ID == strCustomerID
                               select c).FirstOrDefault();
                    if (del != null)
                    {
                        db.CUSTOMER.Remove(del);
                    }

                    db.SaveChanges();

                    MessageBox.Show(string.Format("Delete {0} Successfully.", strCustomerID));
                }

                BindData();
            }
        }

    }

Public Class frmMain
    Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        BindData()
    End Sub

    Private Sub BindData()
        ' Create new entities Object
        Using db = New myDatabaseEntities()

            ' Get data from CUSTOMER
            Dim ds = (From c In db.CUSTOMER
                      Select New With { _
                            c.CUSTOMER_ID, _
                            c.NAME, _
                            c.EMAIL, _
                            c.COUNTRY_CODE, _
                            c.BUDGET, _
                            c.USED _
                     }).ToList()

            ' Assign to DataGridView
            If ds.Count > 0 Then
                ' New DataSource
                Me.myDataGridView.AutoGenerateColumns = False
                Me.myDataGridView.AllowUserToAddRows = False
                Me.myDataGridView.SelectionMode = DataGridViewSelectionMode.FullRowSelect
                Me.myDataGridView.DataSource = ds
            End If

            ' Summary Budget Column
            Dim iSumBudget As Decimal = 0
            For Each row As DataGridViewRow In Me.myDataGridView.Rows
                iSumBudget = iSumBudget + Convert.ToDecimal(row.Cells("BUDGET").Value)
            Next
            Me.lblTotalBudget.Text = String.Format("Total Budget : {0}", iSumBudget.ToString("#,###.00"))

            ' Summary Used Column
            Dim iSumUsed As Decimal = 0
            For Each row As DataGridViewRow In Me.myDataGridView.Rows
                iSumUsed = iSumUsed + Convert.ToDecimal(row.Cells("USED").Value)
            Next
            Me.lblTotalUsed.Text = String.Format("Total Used : {0}", iSumUsed.ToString("#,###.00"))

        End Using
    End Sub

    Private Sub btnDelete_Click(sender As Object, e As EventArgs) Handles btnDelete.Click
        Dim strCustomerID As String = Me.myDataGridView.Rows(Me.myDataGridView.CurrentCell.RowIndex).Cells("CUSTOMER_ID").Value.ToString()

        If MessageBox.Show(String.Format("Are you sure to delete {0}?", strCustomerID), "Confirm.", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button1) = DialogResult.Yes Then

            ' Create new entities from Entities
            Using db = New myDatabaseEntities()
                ' Delete CUSTOMER
                Dim del = (From c In db.CUSTOMER
                           Where c.CUSTOMER_ID = strCustomerID
                           Select c).FirstOrDefault()
                If Not IsNothing(del) Then
                    db.CUSTOMER.Remove(del)
                End If

                db.SaveChanges()

                MessageBox.Show(String.Format("Delete {0} Successfully.", strCustomerID))
            End Using

            BindData()
        End If
    End Sub

End Class