开发实践教程1：试卷生成系统6.15 考题类型管理（FormExamType）

Posted 2021-09-15 VB.Net

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仅管理员可用

增加、更新考题类型，通常情况下，为了防止考题类型删除引发错误，管理员设置一次后就不再操作或仅能更新、不可删除。

窗体设计如下：

 图1-25

具体代码如下：

Imports System.Data.SqlClient

Public Class FormExamType
    Dim connection As SqlConnection


    Private Sub btnClose_Click(sender As Object, e As EventArgs) Handles btnClose.Click
        Me.Close()
    End Sub

    Private Sub FormExamType_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        connection = New SqlConnection(databaseConnString)
        connection.Open()

        Call DrawLv()
    End Sub

    Private Sub DrawLv()
        lvType.Items.Clear()

        Dim command As New SqlCommand
        command.Connection = connection
        command.CommandText = "select 编号,类型名称,类型说明 from 题类型表"

        Dim sqlReader As SqlDataReader
        sqlReader = command.ExecuteReader()

        If sqlReader.HasRows Then
            Do While sqlReader.Read
                Dim lvitem As New ListViewItem()
                lvitem.Text = sqlReader(0)
                lvitem.SubItems.Add(sqlReader(1))
                lvitem.SubItems.Add(sqlReader(2))
                lvType.Items.Add(lvitem)
            Loop
        End If

        sqlReader.Close()
    End Sub

    Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
        Dim typeName As String = txtName.Text.Trim
        Dim typeInfo As String = txtInfo.Text.Trim

        Dim errMsg As String
        errMsg = checkData()
        If errMsg <> "" Then
            MessageBox.Show(errMsg)
            Exit Sub
        End If

        Dim command As New SqlCommand
        command.Connection = connection
        command.CommandText = "insert into 题类型表(类型名称,类型说明) values('" & typeName & "','" & typeInfo & "')"
        command.ExecuteNonQuery()

        Call DrawLv()
    End Sub

    Private Sub btnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click
        Dim typeID As Integer = CType(txtId.Text, Integer)
        Dim typeName As String = txtName.Text.Trim
        Dim typeInfo As String = txtInfo.Text.Trim

        Dim errMsg As String
        errMsg = checkData()
        If errMsg <> "" Then
            MessageBox.Show(errMsg)
            Exit Sub
        End If

        Dim command As New SqlCommand
        command.Connection = connection
        command.CommandText = "update 题类型表 set 类型名称='" & typeName & "',类型说明='" & typeInfo & "' where 编号=" & typeID
        command.ExecuteNonQuery()

        Call DrawLv()
    End Sub

    Private Function checkData() As String
        Dim typeName As String = txtName.Text.Trim
        If typeName = "" Then
            Return "必须输入考题类型名称"
        End If

        For i As Integer = 0 To lvType.Items.Count - 1
            If lvType.Items(i).SubItems(0).Text = typeName Then
                Return "已经存在该考题类型名称，请重新输入"
            End If
        Next

        Return ""
    End Function

    Private Sub lvType_SelectedIndexChanged(sender As Object, e As EventArgs) Handles lvType.SelectedIndexChanged

    End Sub

    Private Sub lvType_MouseClick(sender As Object, e As MouseEventArgs) Handles lvType.MouseClick
        If lvType.Items.Count = 0 Then
            Exit Sub
        End If

        Dim lvHti As ListViewHitTestInfo
        lvHti = lvType.HitTest(e.X, e.Y)

        Dim lvItem As ListViewItem = lvHti.Item
        txtId.Text = lvItem.SubItems(0).Text
        txtName.Text = lvItem.SubItems(1).Text
        txtInfo.Text = lvItem.SubItems(2).Text
    End Sub
End Class

由于.net平台下C#和vb.NET很相似，本文也可以为C#爱好者提供的参考。

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