在敲组合查询的时候，我遇到了很多问题，比如说查询的语法怎么连接啊，怎么让控件中的文本信息也就是说字段名，组合关系对应数据库表中的字段哪？

     也就是说我们要让卡号=Cardno，让姓名=StudentName ，这样我们在查询的时候才方便了，反成不能直接给Combox的text里面上英文的吧？ 于是就定义个函数，让它实现这个功能，函数如下。

<span style="font-size:18px;">Public Function Field(i As String) As String
    Select Case i
        Case "卡号"
    Field = "cardno"
        Case "姓名"
    Field = "studentname"
        Case "上机日期"
    Field = "ondate"
        Case "上机时间"
    Field = "ontime"
        Case "下机日期"       .......    End select
End Function
</span>

<span style="font-size:18px;">Private Sub cmdInqurie_Click()
    Dim ctrl As Control
    Dim mrc As ADODB.Recordset
    Dim txtSQL As String
    Dim Msgtext As String
     '检查条件输入
    If Trim(cmbfeild1.Text) = "" Or Trim(cmboperator1.Text) = "" Or Trim(txt1.Text) = "" Then
        MsgBox "请输入完整的查询条件", , "提示"
        Exit Sub
    End If
    
    Dim i, iCols As Integer '让所有列都居中显示文字
    iCols = MSFlexGrid1.Cols
    For i = 0 To iCols - 1
        MSFlexGrid1.ColAlignment(i) = flexAlignCenterCenter
    Next
    
    txtSQL = "select * from line_info where "
    txtSQL = txtSQL & Trim(Field(cmbfeild1.Text)) & Trim((cmboperator1.Text)) & "'" & Trim(txt1.Text) & "'"
    If Trim(cmbRelation1.Text <> "") Then '第一个组合关系存在
        If Trim(cmbfeild2.Text) = "" Or Trim(cmboperator2.Text = "") Or Trim(txt2.Text = "") Then
            MsgBox "你已经选择了第一个组合关系，请输入第二行查询条件", , "提示"
            Exit Sub
        Else
            txtSQL = txtSQL & Field(Trim(cmbRelation1.Text)) & " " & Field(cmbfeild2.Text) & cmboperator2.Text & "'" & Trim(txt2.Text) & "'"
        End If
    End If
    
    If Trim(cmbRelation2.Text <> "") Then '第二个组合关系存在
        If Trim(cmbfeild3.Text) = "" Or Trim(cmboperator3.Text) = "" Or Trim(txt3.Text) = "" Then
            MsgBox "你已经选择了第二个组合关系，请输入第三行查询条件", , "提示"
            Exit Sub
        Else
            txtSQL = txtSQL & Field(cmbRelation2.Text) & " " & Field(cmbfeild3.Text) & cmboperator3.Text & "'" & Trim(txt3.Text) & "'"
        End If
    End If
    On Error GoTo error1 '错误语句保护，当用户输入查询的格式不对时给出提示信息。    Set mrc = ExecuteSQL(txtSQL, Msgtext)
    If mrc.EOF = True Then '检查信息是否存在，如果不存在给出提示并清空所有文本框
        MsgBox "没有查询到结果，可能会你输入的信息不存在，或者信息矛盾"
        For Each ctrl In Me.Controls
        If TypeOf ctrl Is TextBox Then   '是否为文本框TextBox
            ctrl.Text = ""               '清空所有文本框
        End If
        Next
     
      For Each ctrl In Me.Controls
        If TypeOf ctrl Is ComboBox Then   '是否为文本框TextBox
            ctrl.Text = ""
        End If
      Next
        Exit Sub
    End If
    With MSFlexGrid1
        .Rows = 1
        .TextMatrix(0, 0) = "卡号"
        .TextMatrix(0, 1) = "姓名"
        .TextMatrix(0, 2) = "上机日期"
        ........
        
     Do While Not mrc.EOF
            .Rows = .Rows + 1
            .TextMatrix(.Rows - 1, 0) = Trim(mrc!cardno)
            .TextMatrix(.Rows - 1, 1) = mrc!studentname
            .TextMatrix(.Rows - 1, 2) = mrc!ondate
            .TextMatrix(.Rows - 1, 3) = mrc!OnTime
            ........
            mrc.MoveNext
        Loop
    End With
    mrc.Close
error1:
    MsgBox "你输入的查询信息格式有误，请按标准格式输入。"
End Sub</span>