.NET下，利用二维数组“组合”查询之优化

至于界面层，这里就不再贴图了，和链接博客中的一样。在这里说明一下：下拉列表中的所有汉字不用在frmWorkRecord_Load中定义了，而是通过将下拉列表中的汉字放到ComboBox的Item属性里。

下面就是U层代码了
[vb]
Imports Entity
Imports BLL

Public Class form1

    '定义一个二维数组，使得下拉列表中的汉字与英文对应
    Dim strArr(2, 7) As String

    Private Sub frmWorkRecord_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        '使用二维数组，避免了之前的select case语句
        '实现“教师”和“UserID”、“上机日期”和“OnDate“.....的一一对应
        strArr(0, 0) = "UserID"
        strArr(0, 1) = "OnDate"
        strArr(0, 2) = "OnTime"
        strArr(0, 3) = "OffDate"
        strArr(0, 4) = "OffTime"
        strArr(0, 5) = "Computer"

        '实现“与”和“and”、“或”和“or”的一一对应
        strArr(1, 0) = "and"
        strArr(1, 1) = "or"

    End Sub

    Private Sub cmdOk_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdOk.Click
        Dim arrTeacherE As TeacherE() = {New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE(), New TeacherE()}

        '“字段”下拉列表中与汉字对应英文赋值到arrTeacherE数组中
        arrTeacherE(0).Name = strArr(0, cbxName1.SelectedIndex)
        'ComboBox控件在页面加载时，默认SelectedIndex=-1，而数组下标不能出现负数，故需要进行判断
        If cbxName2.Text = "" Then
            arrTeacherE(1).Name = ""
        Else
            arrTeacherE(1).Name = strArr(0, cbxName2.SelectedIndex)
        End If

        If cbxName3.Text = "" Then
            arrTeacherE(2).Name = ""
        Else
            arrTeacherE(2).Name = strArr(0, cbxName3.SelectedIndex)
        End If

        '将“操作符”赋值到arrTeacherE数组中
        arrTeacherE(3).Operation = cbxOperation1.Text
        arrTeacherE(4).Operation = cbxOperation2.Text
        arrTeacherE(5).Operation = cbxOperation3.Text

        '将“查询条件”赋值到arrTeacherE数组中
        arrTeacherE(6).txtName = txtName1.Text
        arrTeacherE(7).txtName = txtName2.Text
        arrTeacherE(8).txtName = txtName3.Text

        '“组合关系”下拉列表中与汉字对应英文赋值到arrTeacherE数组中
        If cbxCompone1.Text = "" Then
            arrTeacherE(9).Compone = ""
        Else
            arrTeacherE(9).Compone = strArr(1, cbxCompone1.SelectedIndex)
        End If
        '这里的If语句作用同上面的If语句
        If cbxCompone2.Text = "" Then
            arrTeacherE(10).Compone = ""
        Else
            arrTeacherE(10).Compone = strArr(1, cbxCompone2.SelectedIndex)
        End If

        Dim mybll As New TeacherBLL
        Dim dt As New DataTable
        dt = mybll.test(arrTeacherE)
        If dt.Rows.Count() > 0 Then
            DataGridView1.DataSource = dt
        Else
            MessageBox.Show("没有记录")
        End If
    End Sub
End Class

而对于B层，这个功能的业务逻辑不是很复杂，只是调用D层相应的方法，然后返回一个DataTable就可以了（不太符合三层，哈哈）

下面就是D层的代码了，这里用到了SqlHelper，相信大家对SqlHelper很熟悉了，这里就不再赘述了，只是在这里调用一下。
[vb]
Imports Entity
Imports System.Data.SqlClient

Public Class OnDutyTeacher

    Function test(ByVal arrTeacherE() As TeacherE) As DataTable
        Dim strSqlText As String = "select * from Teacher_Info where " & arrTeacherE(0).Name & arrTeacherE(3).Operation & " " & "@txtName1" & arrTeacherE(9).Compone & " " & arrTeacherE(1).Name & arrTeacherE(4).Operation & " " & "@txtName2" & " " & arrTeacherE(10).Compone & " " & arrTeacherE(2).Name & " " & arrTeacherE(5).Operation & "@txtName3" & " "

        Dim param() As SqlParameter
        Dim intInfluencedRecord As Integer

        param = New SqlParameter() {New SqlParameter("@txtName1", SqlDbType.Char, 10), New SqlParameter("@txtName2", SqlDbType.Char, 10), New SqlParameter("@txtName3", SqlDbType.Char, 10)}

        param(0).Value = arrTeacherE(6)

补充：Web开发 , ASP.Net ,