机房收费系统（组合查询）

涉及组合窗体：

学生基本信息维护窗体，学生上机统计信息窗体，操作员工作记录窗体

定义函数：

我们需要定义一个Field函数，用来使VB程序中的字段名和数据库中的列名对应：

Public Function FiledName(StrFiledName As String) As String
    Select Case StrFiledName
    Case "卡号"
        FiledName = "cardno"
    Case "学号"
        FiledName = "studentno"
    Case "姓名"
        FiledName = "studentname"
    Case "性别"
        FiledName = "sex"
    Case "系别"
        FiledName = "department"
    Case "年级"
        FiledName = "grade"
    Case "班级"
        FiledName = "class"
    End Select
End Function

Public Function Relationname(strRelationname As String) As String
    Select Case strRelationname
        Case "与"
            Relationname = "and"
        Case "或"
            Relationname = "or"
    End Select
End Function

然后理清思路，可以自己画个简单的图，判断3个组合关系：

Private Sub Command1_Click()
    Dim txtSQL As String
    Dim MsgText As String
    Dim mrc As ADODB.Recordset

    If ComboZD1.Text = "" Then
        MsgBox "请选择字段名！", vbOKOnly + vbExclamation, "提示"
        ComboZD1.SetFocus
        Exit Sub
    End If

    If ComboCZ1.Text = "" Then
        MsgBox "请选择操作符！", vbOKOnly + vbExclamation, "提示"
        ComboCZ1.SetFocus
        Exit Sub
    End If

    If txtCX1.Text = "" Then
        MsgBox "请输入要查询的内容"
        txtCX1.SetFocus
        Exit Sub
    End If

    txtSQL = "select * from student_Info where " & FiledName(ComboZD1.Text) & ComboCZ1.Text & " '" & txtCX1.Text & "'"

    If Trim(ComboZH1(0).Text) <> "" Then
        If Trim(ComboCZ1.Text) = "" Or Trim(txtCX2.Text) = "" Or Trim(ComboZH1(0).Text) = "" Then
            MsgBox "您选择了第一种组合关系，请输入完整信息再查询", vbExclamation + vbOKOnly, "提示"
            Exit Sub
        Else

            txtSQL = "select * from student_Info where " & FiledName(ComboZD1.Text) & ComboCZ1.Text & "'" _
            & Trim(txtCX1.Text) & "'" & " " & Relationname(ComboZH1(0).Text) & " " & FiledName(ComboZD2.Text) _
            & ComboCZ2.Text & "'" & Trim(txtCX2.Text) & "'"
        End If

    End If

    If Trim(ComboZH1(1).Text) <> "" Then
        If Trim(ComboCZ3.Text) = "" Or Trim(txtCX3.Text) = "" Or Trim(ComboZH1(1).Text) = "" Then
            MsgBox "您选择了第二种组合关系，请输入完整信息再查询", vbExclamation + vbOKOnly, "提示"
            Exit Sub
        Else

            txtSQL = "select * from student_Info where " & FiledName(ComboZD1.Text) & ComboCZ1.Text & "'" _
            & Trim(txtCX1.Text) & "'" & " " & Relationname(ComboZH1(0).Text) & " " & FiledName(ComboZD2.Text) _
            & ComboCZ2.Text & "'" & Trim(txtCX2.Text) & "'" & " " & Relationname(ComboZH1(1).Text) & " " & _
            FiledName(ComboZD3.Text) & ComboCZ3.Text & "'" & Trim(txtCX3.Text) & "'"
        End If
    End If

    Set mrc = ExecuteSQL(txtSQL, MsgText)
    If mrc.EOF Then
        MsgBox "没有您要查找的学生，请重新查询！", vbOKOnly + vbExclamation, "提示"
    Else
        Do While Not mrc.EOF
            With MSHFlexGrid1
                .Rows = .Rows + 1
                .CellAlignment = 4
                .TextMatrix(.Rows - 1, 0) = Trim(mrc.Fields(0))
                .TextMatrix(.Rows - 1, 1) = Trim(mrc.Fields(1))
                .TextMatrix(.Rows - 1, 2) = Trim(mrc.Fields(2))
                .TextMatrix(.Rows - 1, 3) = Trim(mrc.Fields(3))
                .TextMatrix(.Rows - 1, 4) = Trim(mrc.Fields(4))
                .TextMatrix(.Rows - 1, 5) = Trim(mrc.Fields(5))
                .TextMatrix(.Rows - 1, 6) = Trim(mrc.Fields(6))
                .TextMatrix(.Rows - 1, 7) = Trim(mrc.Fields(7))
                .TextMatrix(.Rows - 1, 8) = Trim(mrc.Fields(8))
                .TextMatrix(.Rows - 1, 9) = Trim(mrc.Fields(10))
                .TextMatrix(.Rows - 1, 10) = Trim(mrc.Fields(12))
                .TextMatrix(.Rows - 1, 11) = Trim(mrc.Fields(13))
                .TextMatrix(.Rows - 1, 12) = Trim(mrc.Fields(14))
            End With
            mrc.MoveNext
        Loop
    End If
            mrc.Close
End Sub

总结：

我的这个有点儿太繁杂了，可以让代码更简便一点儿。