Question

我有一个datagridview（有5列：4个文本框和1个组合框），它从mysql中加载数据。这是我使用的代码，当我在所有textbox列中尝试它时，它工作正常。但当我将最后一列更改为组合框时，我收到一条错误消息：

＆＃34; DataGridView中出现以下异常：

System.ArgumentException：DataGridViewComboBoxCell值无效。

要替换此默认对话框，请处理DataError事件。＆＃34;

Private Sub Main_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    sqlconn.ConnectionString = "server=localhost;userid=root;password=12345;database=db_scheduling"
    teacherQuery("SELECT * FROM tbl_teacher ORDER BY id")
End Sub

Sub teacherQuery(ByVal strings)
    Try
        Dim sqlcommand As New MySqlCommand
        Dim sqladapter As New MySqlDataAdapter
        sqlcommand.Parameters.AddWithValue("@id", AddTeacher.txt_AddTeacher_ID.Text)
        sqlcommand.Parameters.AddWithValue("@lname", AddTeacher.txt_AddTeacher_Lname.Text)
        sqlcommand.Parameters.AddWithValue("@fname", AddTeacher.txt_AddTeacher_Fname.Text)
        sqlcommand.Parameters.AddWithValue("@mname", AddTeacher.txt_AddTeacher_Mname.Text)
        sqlcommand.Parameters.AddWithValue("@subject_to_teach", AddTeacher.cmb_AddTeacher_Subject.SelectedItem)
        Dim Table As New DataTable
        With sqlcommand
            .CommandText = strings
            .Connection = sqlconn
        End With
        With sqladapter
            .SelectCommand = sqlcommand
            .Fill(Table)
        End With

        '----HERES THE PROBLEM-----'
        datagrid_Teacher.Rows.Clear()
        For x As Integer = 0 To Table.Rows.Count - 1
            datagrid_Teacher.Rows.Add(Table(x)("id"),
                                      Table(x)("lname"),
                                      Table(x)("fname"),
                                      Table(x)("mname"),
                                      Table(x)("subject_to_teach"))
        Next
        '---------------------------'

        'Bold header
        With datagrid_Teacher.ColumnHeadersDefaultCellStyle
            .Font = New Font(datagrid_Teacher.Font, FontStyle.Bold)
        End With
    Catch ex As Exception
        MessageBox.Show("ERROR: " + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End Try
End Sub

编辑：这里的问题是在datagridview中添加数据（组合框（subject_to_teach列））

Answer 1

尝试使用此方法而不是datagrid_Teacher.Rows.Add方式：

datagrid_Teacher.Datasource = Table;
datagrid_Teacher.Databind();

或者在你的代码上添加它（Gridview Dataerror的事件处理程序）：

private void ctrldataGridView_DataError(object sender, DataGridViewDataErrorEventArgs e)
       {
          //do nothing
       }

Answer 2

我设法通过删除设计中的组合框列并在代码中添加组合框列，并将我的代码修改为：

Sub teacherQuery(ByVal strings)
    Try
        Dim sqlcommand As New MySqlCommand
        Dim sqladapter As New MySqlDataAdapter
        sqlcommand.Parameters.AddWithValue("@id", AddTeacher.txt_AddTeacher_ID.Text)
        sqlcommand.Parameters.AddWithValue("@lname", AddTeacher.txt_AddTeacher_Lname.Text)
        sqlcommand.Parameters.AddWithValue("@fname", AddTeacher.txt_AddTeacher_Fname.Text)
        sqlcommand.Parameters.AddWithValue("@mname", AddTeacher.txt_AddTeacher_Mname.Text)
        sqlcommand.Parameters.AddWithValue("@subject_to_teach", AddTeacher.cmb_AddTeacher_Subject.SelectedItem)
        sqlcommand.Parameters.AddWithValue("@search", "" + txt_TeacherSearch.Text + "%")
        Dim Table As New DataTable
        With sqlcommand
            .CommandText = strings
            .Connection = sqlconn
        End With
        With sqladapter
            .SelectCommand = sqlcommand
            .Fill(Table)
        End With
'---THIS IS WHAT I ADDED
        Dim combo As New DataGridViewComboBoxColumn
        Dim row As DataRow

        With combo
            For Each row In Table.Rows
                .Items.Add(row.Item("subject_to_teach").ToString)
                .Name = "Teaching Subject"
            Next
        End With
        datagrid_Teacher.Columns.Add(combo)
'-----------------------
        datagrid_Teacher.Rows.Clear()
        For x As Integer = 0 To Table.Rows.Count - 1
            datagrid_Teacher.Rows.Add(Table(x)("id"),
                                      Table(x)("lname"),
                                      Table(x)("fname"),
                                      Table(x)("mname"),
                                      Table(x)("subject_to_teach"))
        Next

        'Bold header
        With datagrid_Teacher.ColumnHeadersDefaultCellStyle
            .Font = New Font(datagrid_Teacher.Font, FontStyle.Bold)
        End With
    Catch ex As Exception
        MessageBox.Show("ERROR: " + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End Try
End Sub

和这个

Private Sub datagrid_Teacher_DataError(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles datagrid_Teacher.DataError
    'ERROR HANDLER
End Sub

如何从mysql -vb.net填充datagridview组合框

2 个答案: