在机房收费系统当中，有好几个窗体设计到了组合查询的问题，在这篇博客当中我就说一下组合查询的事
首先，组合查询的窗体如下所示：
为简单起见给图中控件的命名ComboBox控件的命名左边三列分别为combo（1，2，3），中间的为combo（4,5,6），右边的为（7,8）；文本框的命名就是Text（1,2,3）
查询语句如下所示：
Private Sub cmdCheck_Click()
Dim ctrl As Control Dim mrc As ADODB.Recordset Dim txtSQL As String Dim Msgtext As String Dim i As Integer If Combo7.Text = "" Then If Trim(Text1.Text) = "" Or Trim(Combo1.Text) = "" Or Trim(Combo4.Text) = "" Then MsgBox "请输入完整的查询条件", , "提示" Exit Sub Else txtSQL = "select * from Line_info where " & Trim(field(Combo1.Text)) & Trim(Combo4.Text) & "'" & Trim(Text1.Text) & "'" End If Else If Combo8.Text = "" Then If Trim(Text2.Text) = "" Or Trim(Combo2.Text) = "" Or Trim(Combo5.Text) = "" Then MsgBox "请输入完整的查询条件", , "提示" Exit Sub Else txtSQL = "select * from Line_info where " & Trim(field(Combo1.Text)) & Trim(Combo4.Text) & "'" & Trim(Text1.Text) & "'" & " " & Trim(field(Combo7.Text)) & " " & Trim(field(Combo2.Text)) & Trim(Combo5.Text) & "'" & Trim(Text2.Text) & "'" End If Else If Trim(Text3.Text) = "" Or Trim(Combo3.Text) = "" Or Trim(Combo6.Text) = "" Then MsgBox "请输入完整的查询条件", , "提示" Exit Sub Else txtSQL = "select * from Line_info where " & Trim(field(Combo1.Text)) & Trim(Combo4.Text) & "'" & Trim(Text1.Text) & "'" & " " & Trim(field(Combo7.Text)) & " " & Trim(field(Combo2.Text)) & Trim(Combo5.Text) & "'" & Trim(field(Text2.Text)) & "'" & " " & Trim(field(Combo8.Text)) & " " & Trim(field(Combo3.Text)) & Trim(Combo6.Text) & "'" & Trim(Text3.Text) & "'" End If End If End If 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，请检查输入信息！", vbOKOnly + vbExclamation, "提示" Call Cancel Exit Sub End If With MSHFlexGrid1 .Rows = 1 .TextMatrix(0, 0) = "卡号" .TextMatrix(0, 1) = "姓名" .TextMatrix(0, 2) = "上机日期" .TextMatrix(0, 3) = "上机时间" .TextMatrix(0, 4) = "下机日期" .TextMatrix(0, 5) = "下机时间" .TextMatrix(0, 6) = "消费金额" .TextMatrix(0, 7) = "余额" .TextMatrix(0, 8) = "备注" Do While Not mrc.EOF .Rows = .Rows + 1 .TextMatrix(.Rows - 1, 0) = mrc.Fields(1).Value & "" .TextMatrix(.Rows - 1, 1) = mrc!studentname .TextMatrix(.Rows - 1, 2) = Trim(mrc.Fields(6).Value & "") .TextMatrix(.Rows - 1, 3) = Trim(mrc.Fields(7).Value & "") .TextMatrix(.Rows - 1, 4) = Trim(mrc.Fields(8).Value & "") .TextMatrix(.Rows - 1, 5) = Trim(mrc.Fields(9).Value & "") .TextMatrix(.Rows - 1, 6) = Trim(mrc.Fields(10).Value & "") .TextMatrix(.Rows - 1, 7) = Trim(mrc.Fields(11).Value & "") .TextMatrix(.Rows - 1, 8) = Trim(mrc.Fields(12).Value & "") mrc.MoveNext Loop End With mrc.Close
End Sub语句虽然是看似简单，但是其中所含的信息无穷啊。在敲代码的时候千万不能忘记的空格的使用。
当然，大家也看到了在代码部分有一个调用“call cancel”，大家可能会说这是什么啊，没见过啊！
这是我为了方便书写而定义的一个过程，代码如下：
Public Function Cancel()这个过程主要是用于清空已填写的数据的
Combo1.Text = ""
Combo2.Text = ""
Combo3.Text = ""
Combo4.Text = ""
Combo5.Text = ""
Combo6.Text = ""
Combo7.Text = ""
Combo8.Text = ""
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
With MSHFlexGrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(0, 0) = ""
.TextMatrix(0, 1) = ""
.TextMatrix(0, 2) = ""
.TextMatrix(0, 3) = ""
.TextMatrix(0, 4) = ""
.TextMatrix(0, 5) = ""
.TextMatrix(0, 6) = ""
.TextMatrix(0, 7) = ""
.TextMatrix(0, 8) = ""
.TextMatrix(1, 0) = ""
.TextMatrix(1, 1) = ""
.TextMatrix(1, 2) = ""
.TextMatrix(1, 3) = ""
.TextMatrix(1, 4) = ""
.TextMatrix(1, 5) = ""
.TextMatrix(1, 6) = ""
.TextMatrix(1, 7) = ""
.TextMatrix(1, 8) = ""
End With
End Function
还有一个要说明的就是field过程，这个过程是为了方便我们查询数据库而存在的，定义过程如下：
Public Function field(comboX As String) As String这篇文章的内容就这么多了，就上图的“导出为Excel功能”请看《机房收费系统问题集锦（三）——导出为Excel》
Select Case comboX
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"
field = "offdate"
Case "下机时间"
field = "offtime"
Case "消费金额"
field = "consume"
Case "余额"
field = "cash"
Case "备注"
field = "status"
Case "与"
field = "and"
Case "或"
field = "or"
End Select
End Function