组合查询 ——vb
机房收费系统中需要组合查询，如图
首先，我分析了查询的流程，并画了流程图，如下：
思路总结好了，下面就是代码的编写了（以学生上机统计信息为例）：
Dim mrc As ADODB.Recordset
Dim txtSQL As String
Dim Msgtxt As String
If Combo3(0).Text = "" Then '不需要组合查询，第一行有为空值时提示错误信息
If Combo1(0).Text = "" Then
MsgBox "请选择字段名", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else
If Combo2(0).Text = "" Then
MsgBox "请选择操作符", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else
If Text1.Text = "" Then
MsgBox "请填写要查询的内容", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else '组合关系框为空且条件成立时，建立的查询，只有第一行"
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
txtSQL = "select * from line_info where "
txtSQL = txtSQL & FName(Combo1(0).Text) & Trim(Combo2(0).Text) & "'" & Trim(Text1.Text) & "'"
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Set mrc = ExecuteSQL(txtSQL, Msgtxt)
If Not (mrc.BOF And mrc.EOF) Then
MSFlexGrid1.Rows = 1
MSFlexGrid1.CellAlignment = 4
MSFlexGrid1.TextMatrix(0, 0) = "卡号"
MSFlexGrid1.TextMatrix(0, 1) = "姓名"
MSFlexGrid1.TextMatrix(0, 2) = "上机日期"
MSFlexGrid1.TextMatrix(0, 3) = "上机时间"
MSFlexGrid1.TextMatrix(0, 4) = "下机日期"
MSFlexGrid1.TextMatrix(0, 5) = "下机时间"
MSFlexGrid1.TextMatrix(0, 6) = "消费金额"
MSFlexGrid1.TextMatrix(0, 7) = "金额"
MSFlexGrid1.TextMatrix(0, 8) = "备注"
Do While Not mrc.EOF '显示数据
With MSFlexGrid1
.Rows = .Rows + 1 '这种方式也可防止空白行的出现
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = mrc.Fields(1)
.TextMatrix(.Rows - 1, 1) = mrc.Fields(2)
.TextMatrix(.Rows - 1, 2) = Format(mrc.Fields(6), "yyyy-mm-dd")
.TextMatrix(.Rows - 1, 3) = mrc.Fields(7)
.TextMatrix(.Rows - 1, 4) = Format(mrc.Fields(8), "yyyy-mm-dd")
.TextMatrix(.Rows - 1, 5) = mrc.Fields(9)
.TextMatrix(.Rows - 1, 6) = mrc.Fields(11)
.TextMatrix(.Rows - 1, 7) = mrc.Fields(12)
.TextMatrix(.Rows - 1, 8) = mrc.Fields(13)
mrc.MoveNext
End With
Loop
Else
MsgBox "该条件下没有记录！"
End If
End If
End If
End If
End If
If Not (Combo3(0).Text = "") Then 'combo3（0）不为空时，分两行或三行查询
If (Combo1(0).Text = "" Or Combo1(1).Text = "") Then
MsgBox "请选择字段名", vbOKOnly + vbExclamation, "警告" '第一行与第二行都不能有空值，否则报错
Exit Sub
Else
If (Combo2(0).Text = "" Or Combo2(1).Text = "") Then
MsgBox "请选择操作符", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else
If (Text1.Text = "" Or Text2.Text = "") Then
MsgBox "请填写要查询的内容", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else
If Combo3(1).Text = "" Then 'combo3（1）为空值时，前两行查询
txtSQL = "select * from line_info where "
txtSQL = txtSQL & FName(Combo1(0).Text) & " " & Trim(Combo2(0).Text) & "'" & Trim(Text1.Text) & "'" & FName(Combo3(0).Text) & " " & FName(Combo1(1).Text) & Combo2(1).Text & "'" & Trim(Text2.Text) & "'"
End If
If Not Combo3(1).Text = "" Then 'combo3（1）不为空值时，三行查询
If (Combo1(2).Text = "") Then
MsgBox "请选择条件3字段名", vbOKOnly + vbExclamation, "警告" '第一行与第二行都不能有空值，否则报错
Exit Sub
Else
If (Combo2(2).Text = "") Then
MsgBox "请选择条件3操作符", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else
If (Text3.Text = "") Then
MsgBox "请填写条件3要查询的内容", vbOKOnly + vbExclamation, "警告"
Exit Sub
Else '没有空值
txtSQL = "select * from line_info where "
txtSQL = txtSQL & FName(Combo1(0).Text) & Trim(Combo2(0).Text) & "'" & Trim(Text1.Text) & "'" & FName(Combo3(0).Text) & " " & FName(Combo1(1).Text) & Trim(Combo2(1).Text) & "'" & Trim(Text2.Text) & "' " & FName(Combo3(1).Text) & " " & FName(Combo1(2).Text) & Trim(Combo2(2).Text) & "'" & Trim(Text3.Text) & "'"
End If
End If
End If
End If
End If
End If
End If
End If
Set mrc = ExecuteSQL(txtSQL, Msgtxt)
If Not (mrc.BOF And mrc.EOF) Then
MSFlexGrid1.Rows = 1
MSFlexGrid1.CellAlignment = 4
MSFlexGrid1.TextMatrix(0, 0) = "卡号"
MSFlexGrid1.TextMatrix(0, 1) = "姓名"
MSFlexGrid1.TextMatrix(0, 2) = "上机日期"
MSFlexGrid1.TextMatrix(0, 3) = "上机时间"
MSFlexGrid1.TextMatrix(0, 4) = "下机日期"
MSFlexGrid1.TextMatrix(0, 5) = "下机时间"
MSFlexGrid1.TextMatrix(0, 6) = "消费金额"
MSFlexGrid1.TextMatrix(0, 7) = "余额"
MSFlexGrid1.TextMatrix(0, 8) = "备注"
Do While Not mrc.EOF '显示数据
With MSFlexGrid1
.Rows = .Rows + 1 '这种方式也可防止空白行的出现
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = mrc.Fields(1)
.TextMatrix(.Rows - 1, 1) = mrc.Fields(2)
.TextMatrix(.Rows - 1, 2) = Format(mrc.Fields(6), "yyyy-mm-dd")
.TextMatrix(.Rows - 1, 3) = mrc.Fields(7)
.TextMatrix(.Rows - 1, 4) = Format(mrc.Fields(8), "yyyy-mm-dd")
.TextMatrix(.Rows - 1, 5) = mrc.Fields(9)
.TextMatrix(.Rows - 1, 6) = mrc.Fields(11)
.TextMatrix(.Rows - 1, 7) = mrc.Fields(12)
.TextMatrix(.Rows - 1, 8) = mrc.Fields(13)
mrc.MoveNext
End With
Loop
Else
MsgBox "该条件下没有记录！"
End If
mrc.Close
逻辑不难，但是查询的时候我的思维有些问题，太麻烦了 ，在跟别人交流时，发现这种查询方法比我的简单多了，学到了很多，尤其是思维方式，自己应该积极转变，多多学习。
txtSQL = "select * from line_info where " txtSQL = txtSQL & ...