mysql - 如何过滤3个相关的datagridviews

我有4个DataGridViews，它们显示主要部门和3个子部门：主要部门，子部门1，SubDepartment2和SubDepartment3。
我想单击Main Department，并希望所有其他DataGrid基于它们上方的DataGrid中的列进行重新过滤。
例如。
SubDepartment1将显示与MainDepartment相关的记录
SubDepartment2将显示与SubDepartment1相关的记录
SubDepartment3将显示与SubDepartment2相关的记录

我有一点工作。我编写了填充每个DataGrid的方法，然后单击MainDepartment DataGrid中的记录时调用了所有这些方法。

这会加载主部门

Private Sub loadmaindept()

    'Dim connstr As String = "database=fabjobs;data source=localhost;userid=root;password=1234"
    Dim connstr As String = ("server='" & My.Settings.setserver & "';
                                   userid='" & My.Settings.setusername & "';
                                   password='" & My.Settings.setpassword & "';
                                   database='" & My.Settings.setdatabase & "'")
    Dim conn As New MySqlConnection(connstr)
    Dim query As String = "select * from maindepartment"

    Try
        conn.Open()
        Dim da As New MySqlDataAdapter(query, conn)
        Dim ds As New DataSet
        da.Fill(ds)
        dgmaindept.DataSource = ds.Tables(0)
        dgmaindept.Refresh()

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Close()
        conn.Dispose()
    End Try
End Sub

这将加载与主要部门相关的子部门1

Private Sub loadsub1dept()

    'Dim connstr As String = "database=fabjobs;data source=localhost;userid=root;password=1234"
    Dim connstr As String = ("server='" & My.Settings.setserver & "';
                                   userid='" & My.Settings.setusername & "';
                                   password='" & My.Settings.setpassword & "';
                                   database='" & My.Settings.setdatabase & "'")
    Dim conn As New MySqlConnection(connstr)
    Dim query As String = "select * from sub1department where MainDptid = '" & dgmaindept.CurrentRow.Cells(0).Value.ToString & "'"

    Try
        conn.Open()
        Dim da As New MySqlDataAdapter(query, conn)
        Dim ds As New DataSet
        da.Fill(ds)
        dgsub1dept.DataSource = ds.Tables(0)
        dgsub1dept.Refresh()

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Close()
        conn.Dispose()
    End Try
End Sub

这将加载与子部门1相关的子部门2

Private Sub loadsub2dept()

    'Dim connstr As String = "database=fabjobs;data source=localhost;userid=root;password=1234"
    Dim connstr As String = ("server='" & My.Settings.setserver & "';
                                   userid='" & My.Settings.setusername & "';
                                   password='" & My.Settings.setpassword & "';
                                   database='" & My.Settings.setdatabase & "'")
    Dim conn As New MySqlConnection(connstr)
    Dim query As String = "select * from sub2department where Sub1Dptid = '" & dgsub1dept.CurrentRow.Cells(0).Value.ToString & "'"

    Try
        conn.Open()
        Dim da As New MySqlDataAdapter(query, conn)
        Dim ds As New DataSet
        da.Fill(ds)
        dgsub2dept.DataSource = ds.Tables(0)
        dgsub2dept.Refresh()

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Close()
        conn.Dispose()
    End Try
End Sub

这将加载与Sub Department2相关的Sub Department 3

Private Sub loadsub3dept()

    'Dim connstr As String = "database=fabjobs;data source=localhost;userid=root;password=1234"
    Dim connstr As String = ("server='" & My.Settings.setserver & "';
                                   userid='" & My.Settings.setusername & "';
                                   password='" & My.Settings.setpassword & "';
                                   database='" & My.Settings.setdatabase & "'")

    Dim conn As New MySqlConnection(connstr)
        Dim query As String = "select * from sub3department where Sub2Dptid = '" & dgsub2dept.CurrentRow.Cells(0).Value.ToString & "'"

    Try
        conn.Open()
        Dim da As New MySqlDataAdapter(query, conn)
        Dim ds As New DataSet
        da.Fill(ds)
        dgsub3dept.DataSource = ds.Tables(0)
        dgsub3dept.Refresh()

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        conn.Close()
        conn.Dispose()
    End Try
End Sub

该代码调用子部门的所有其他方法

Private Sub dgmaindept_CellClick(sender As Object, e As DataGridViewCellEventArgs) Handles dgmaindept.CellClick

    Try
        Dim index As Integer
        index = e.RowIndex
        Dim selectedrow As DataGridViewRow
        selectedrow = dgmaindept.Rows(index)

        lblmainid.Text = selectedrow.Cells(0).Value.ToString()
        txtmaindeptno.Text = selectedrow.Cells(1).Value.ToString()
        txtmaindescription.Text = selectedrow.Cells(2).Value.ToString()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try

    loadsub1dept()
    loadsub2dept()
    loadsub3dept()

End Sub

当我单击主部门中的任何记录时，我希望网格自动全部过滤。只要我在子部门1中有记录，它就可以工作，但是当我单击没有子部门1记录的主部门记录时，我会在子部门2方法中得到Null引用未处理错误。

最佳答案

将您的loadXdept()子项也放入try / catch处理程序中