更新数据网格视图？

Question

我想知道如何更新我的 DataGridView 中的 selected 行。我希望我的系统能够识别我从我的数据网格视图中 select 编辑的现有信息行（顺便说一句，我已将其设置为整行 select）和 update/edit 通过更改信息它们与我用来添加它们的文本框和组合框。我的 table 中的所有内容都设置为文本数据类型，除了 ID 是自动编号。但是，我在下面使用的代码中遇到错误。任何帮助将不胜感激！谢谢 :)（由于我没有足够的声誉，我将在错误的屏幕截图中提供 link。） * 当我用方括号括起部分时出现新错误 http://i.imgur.com/gs8rVhB.png

Imports System.Data.OleDb

Public Class AdmMain

Dim con As New OleDbConnection

Sub fillcombo()
    strsql = " select yrgr from yearandgrade"
    Dim acscmd As New OleDb.OleDbCommand
    acscmd.CommandText = strsql
    acscmd.Connection = acsconn
    acsdr = acscmd.ExecuteReader

    While (acsdr.Read())
        cboyr.Items.Add(acsdr("yrgr"))
    End While
    acscmd.Dispose()
    acsdr.Close()
End Sub

Sub comb2()
    strsql = " select sections from sectio"
    Dim acscmd As New OleDb.OleDbCommand
    acscmd.CommandText = strsql
    acscmd.Connection = acsconn
    acsdr = acscmd.ExecuteReader

    While (acsdr.Read())
        cbosec.Items.Add(acsdr("sections"))
    End While
    acscmd.Dispose()
    acsdr.Close()
End Sub

Private Sub LinkLabel1_LinkClicked(sender As System.Object, e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
    If MessageBox.Show("Are you sure you want to logout?", "Logout", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then
        MessageBox.Show("You have successfully logged out of VCM's Library Information System!", "Logout Confirmed")
        Me.Close()
        LoginUser.Show()
    End If
End Sub

Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
    Me.TxtID.Text = ""
    Me.txtFName.Text = ""
    Me.txtMName.Text = ""
    Me.txtLName.Text = ""
    Me.cboyr.Text = ""
    Me.cbosec.Text = ""
    Me.TxtID.Focus()
End Sub

Private Sub AdmMain_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Module1.connect()
    Me.fillcombo()
    Me.comb2()


    con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=C:\Thesis\Thesis\Database1.accdb"

    con.Open()

    datagridshow()
End Sub

Private Sub datagridshow()
    Dim ds As New DataSet
    Dim dt As New DataTable
    ds.Tables.Add(dt)
    Dim da As New OleDbDataAdapter

    da = New OleDbDataAdapter("select * from students ", con)
    da.Fill(dt)

    DataGridView1.DataSource = dt.DefaultView

    con.Close()
End Sub
Private Sub btnAdd_Click(sender As System.Object, e As System.EventArgs) Handles btnAdd.Click
    Dim rbdtext As String = cboyr.SelectedItem.ToString
    Dim uno As String = cbosec.SelectedItem.ToString

    Try
        Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;" & _
                     "Data Source=C:\Thesis\Thesis\Database1.accdb"
        Dim sqlquery As String = "INSERT INTO students " & _
            "(StudentID, FirstName,MiddleName,LastName,Yr, [Section]) " & _
            "VALUES (@studid, @fname,@mname,@lname,@yr, @sec)"

        ' Use this form to initialize both connection and command to 
        ' avoid forgetting to set the appropriate properties....

        Using conn = New System.Data.OleDb.OleDbConnection(cnString)
            Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)

                conn.Open()
                cmd.Parameters.AddWithValue("@studid", TxtID.Text)
                cmd.Parameters.AddWithValue("@fname", txtFName.Text)
                cmd.Parameters.AddWithValue("@mname", txtMName.Text)
                cmd.Parameters.AddWithValue("@lname", txtLName.Text)
                cmd.Parameters.AddWithValue("@yr", rbdtext)
                cmd.Parameters.AddWithValue("@sec", uno)

                If TxtID.Text = "" Or txtFName.Text = "" Or txtMName.Text = "" Or txtLName.Text = "" Or cboyr.SelectedIndex = -1 Or cbosec.SelectedIndex = -1 Then
                    MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                    Return
                Else
                    Dim rowsInserted = cmd.ExecuteNonQuery()
                    If rowsInserted > 0 Then
                        MessageBox.Show("One record successfully added!", "Added!")
                        datagridshow()
                    Else
                        MessageBox.Show("Failure to add new record!", "Failure!")
                    End If
                End If

            End Using
        End Using
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
End Sub

Private Sub TxtID_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) Handles TxtID.KeyPress

    '97 - 122 = Ascii codes for simple letters
    '65 - 90  = Ascii codes for capital letters
    '48 - 57  = Ascii codes for numbers

    If Asc(e.KeyChar) <> 8 Then
        If Asc(e.KeyChar) < 48 Or Asc(e.KeyChar) > 57 Then
            e.Handled = True
        End If
    End If

End Sub

Private Sub btnEdit_Click(sender As System.Object, e As System.EventArgs) Handles btnEdit.Click
    Dim rbdtext As String = cboyr.SelectedItem.ToString
    Dim uno As String = cbosec.SelectedItem.ToString

    Try
        Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;" & _
                     "Data Source=C:\Thesis\Thesis\Database1.accdb"
        Dim sqlquery As String = "UPDATE Students SET StudentID = @STUDID, FirstName = @FNAME, MiddleName = @MNAME, LastName= @LNAME, Yr = @YRR, [Section] = @SEC WHERE StudentID = @STUDID, FirstName =@FNAME, MiddleName = @MNAME, LastName= @LNAME, Yr = @YRR, [Section] = @SEC"



        ' Use this form to initialize both connection and command to 
        ' avoid forgetting to set the appropriate properties....

        Using conn = New System.Data.OleDb.OleDbConnection(cnString)
            Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)

                conn.Open()
                cmd.Parameters.AddWithValue("@STUDID", TxtID.Text)
                cmd.Parameters.AddWithValue("@FNAME", txtFName.Text)
                cmd.Parameters.AddWithValue("@MNAME", txtMName.Text)
                cmd.Parameters.AddWithValue("@LNAME", txtLName.Text)
                cmd.Parameters.AddWithValue("@YRR", rbdtext)
                cmd.Parameters.AddWithValue("@SEC", uno)

                If TxtID.Text = "" Or txtFName.Text = "" Or txtMName.Text = "" Or txtLName.Text = "" Or cboyr.SelectedIndex = -1 Or cbosec.SelectedIndex = -1 Then
                    MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                    Return
                Else
                    Dim rowsInserted = cmd.ExecuteNonQuery()
                    If rowsInserted > 0 Then
                        MessageBox.Show("One record successfully updated!", "Updated!")
                        datagridshow()
                    Else
                        MessageBox.Show("Failure to update new record!", "Failure!")
                    End If
                End If

            End Using
        End Using
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try
End Sub

End Class

Answer 1

UPDATE...WHERE 表达式的语法需要一个唯一标识要更新的记录的条件。如果条件是由多个 field/value 组成的表达式，则应使用不使用逗号的 AND 或 OR 运算符组合这些条件。

通常 WHERE 子句中的条件使用 table 的 PRIMARY KEY 标识要更新的记录（在您的情况下，这似乎是 StudentID 字段），因此您只需要编写

Dim sqlquery As String = "UPDATE Students SET FirstName = @FNAME, " &_ 
                         "MiddleName = @MNAME, LastName= @LNAME, Yr = @YRR, " & _ 
                         "[Section] = @SEC " & _ 
                         "WHERE StudentID = @STUDID"

请注意，如果 StudentID 是 PRIMARYKEY，您不要尝试 change/update 它因为这可能会导致您的其他数据库 table 与学生 table 引用（有关系）table

最后，OleDb 提供程序无法通过名称识别参数，提供程序希望传递的每个参数的顺序与参数占位符在命令文本中出现的顺序相同（它使用参数的位置将值传递给数据库引擎），因此您还需要更改为 UPDATE

设置参数集合的顺序

cmd.Parameters.AddWithValue("@FNAME", txtFName.Text)
cmd.Parameters.AddWithValue("@MNAME", txtMName.Text)
cmd.Parameters.AddWithValue("@LNAME", txtLName.Text)
cmd.Parameters.AddWithValue("@YRR", rbdtext)
cmd.Parameters.AddWithValue("@SEC", uno)

cmd.Parameters.AddWithValue("@STUDID", TxtID.Text)

更新数据网格视图？

Updating Datagridview?

vb.net

datagridview