كيف أبحث عن قيمة داخل Datagridview في تطبيق Vb.net؟

الملاحظ هو أنك أنشأت DB Objects جديد مرة أخرى، في حين أن DataAdapter و CommandBuilder يجب ملؤها مرة أخرى، مما يعني تكرار الكود، وكتابته بشكل كثيف، لذا أقترح عليك كتابة الكود بالشكل التالي:

• تعريف المتغيرات عند إنشاء  النافذة Form:

Public Class Form1
    ' declare some persistant DB objects
    Private myDT As DataTable
    Private myDA As OleDbDataAdapter
    Private myCB As OleDbCommandBuilder
    Private myStudentsDataView As DataView

    Private dbConnStr As String = "(your connection string)"

• تعريف وإنشاء الكائنات objects:

' initialize the objects
Dim sql = "SELECT * FROM Students"

' this is the ONLY place you use NEW 
' with these objects
myDT = New DataTable
myDA = New OleDbDataAdapter

' create, use and dispose of the connection each time you need one
' even simpler is to use a GetConnection method like I linked 
' to you previously
Using con As OleDbConnection = New OleDbConnection(dbConnStr)
    Using cmd As New OleDbCommand(sql, con)
        con.Open()

        myDA.SelectCommand = cmd
        myDA.Fill(myDT)

        ' "teach" the DA how to Update and Add:
        myDA.UpdateCommand = myCB.GetUpdateCommand
        myDA.InsertCommand = myCB.GetInsertCommand

        myStudentsDataView = myDT.DefaultView

        dgvStudents.DataSource = myStudentsDataView
    End Using

End Using

• وظيفة إضافة Student جديد:

Private Sub AddStudent()
    ' no need to create DataAdapter
    ' because it has form level Scope
    Dim dr = myDT.NewRow
    dr.Item("FirstName") = textbox1.text
    dr.Item("LastName") = textbox2.text
    ' etc etc

    ' add the new row to the datatable
    myDT.Rows.Add(dr)

    ' create a new connection every time
    Using dbcon As New OleDbConnection(dbConnStr)
        ' maybe do this to check:
        If myDA.InsertCommand Is Nothing Then
            myDA.InsertCommand = myCB.GetInsertCommand
        End If

        ' with a persistent DA and CB, this is all you 
        ' need to add a row:
        myDA.Update(myDT)
    End Using

End Sub

• وظيفة البحث:

Private Sub Search(txt As String)
    myStudentsDataView.RowFilter = String.Format("LastName = {0}", txt)

• لإلغاء البحث:

myStudentsDataView = myDT.DefaultView