机房收费系统之组合查询
机房收费系统中，组合查询也是一个很难解决的问题。首先我们要理清思路，了解它的逻辑关系，才能更好的完成它，同时更要注重细节。
1. 无组合关系，即只有第一层查询。
2. 第一个组合关系，第一层和第二层查询。组合关系分为“与”和“或”关系。
3. 第二组合关系，第一层，第二层和第三层。组合关系分为“与与”，“或或”，“与或”，“或与”关系。
一些细节：”姓名”、“教师”、“机器名”只有等于和不等于，无大于和小于。
“上机日期”和”上机时间”，作为条件查询时，要有提醒，正确输入日期或时间格式。
If Combo1.Text = "上机日期" Then
If Not IsDate(Text1.Text) Then
MsgBox "上机日期应输入日期格式（yyyy-mm-dd）！", vbOKOnly + vbExclamation, "提醒"
End If
End If
If Combo1.Text = "上机时间" Then
If Not IsDate(Text1.Text) Then
MsgBox "上机时间应输入日期格式（yy:mm:dd）！", vbOKOnly + vbExclamation, "提醒"
End If
下面是组合查询代码：
Dim txtSQL As String '定义字符串变量，表示查询语句
Dim Msgtext As String '定义字符串变量，返回查询语句
Dim mrc As ADODB.Recordset '定义数据集对象
'无组合关系，即只有第一层查询
txtSQL = "select * from worklog_Info where "
If Trim$(Combo7.Text) = "" Then
'如果所选内容为空，则提示“请把您的输入项填写完整”
'无组合关系，即只有第一层查询
If Trim$(Combo1.Text) = "" Or Trim$(Combo4.Text) = "" Or Trim$(Text1.Text) = "" Then
MsgBox "请把您的输入项填写完整", vbOKOnly + vbExclamation, "警告！"
Exit Sub
Else
'执行sql语句
txtSQL = txtSQL & Combo1.Text & Combo4.Text & "'" & Text1.Text & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo1.SetFocus
Text1.Text = ""
mygrid1.Clear
Exit Sub
Else '数据库中有记录时
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
End If
Set mrc = Nothing '释放记录集
End If
'第二组合关系，第一层，第二层和第三层。组合关系分为“与与”，“或或”，“与或”，“或与”关系。
txtSQL = "select * from worklog_Info where "
If Not Trim$(Combo7.Text) = "" Then
'确保输入选项完整
If Trim$(Combo1.Text) = "" Or Trim$(Combo4.Text) = "" Or Trim$(Text1.Text) = "" Or _
Trim$(Combo2.Text) = "" Or Trim$(Combo5.Text) = "" Or Trim$(Text2.Text) = "" Then
MsgBox "请把您的输入项填写完整", vbOKOnly + vbExclamation, "警告！"
Exit Sub
Else
If Combo7.Text = "与" Then '当Combo7为"与"时
txtSQL = txtSQL & Combo1.Text & " " & Trim$(Combo4.Text) & "'" & _
Trim$(Text1.Text) & "'" & " " & "And" & " " & Combo2.Text & " " & _
Trim$(Combo5.Text) & "'" & Text2.Text & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo2.SetFocus
Text2.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
Else
'当Combo7为"或"时
txtSQL = txtSQL & Combo1.Text & " " & Trim$(Combo4.Text) & "'" & _
Trim$(Text1.Text) & "'" & " " & "or" & " " & Combo2.Text& " " & _
Trim$(Combo5.Text) & "'" & Text2.Text & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo2.SetFocus
Text2.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
'调用添加函数，把数据载入到flexgrid控件中
End If
End If
End If
Set mrc = Nothing '释放记录集
End If
'第二组合关系，第一层，第二层和第三层。组合关系分为“与与”，“或或”，“与或”，“或与”关系。
txtSQL = "select * from worklog_Info where "
If Not Trim$(Combo8.Text) = "" Then
'确保输入选项完整
If Trim$(Combo1.Text) = "" Or Trim$(Combo4.Text) = "" Or Trim$(Text1.Text) = "" Or _
Trim$(Combo2.Text) = "" Or Trim$(Combo5.Text) = "" Or Trim$(Text2.Text) = "" _
Or Trim(Combo3.Text) = "" Or Trim(Combo6.Text) = "" Or Trim(Text3.Text) = "" Then
MsgBox "请把您的输入项填写完整", vbOKOnly + vbExclamation, "警告！"
Exit Sub
Else
'两个组合关系均为“与”时
If Combo7.Text = "与" And Combo8.Text = "与" Then
txtSQL = txtSQL & Combo1.Text & " " & Trim$(Combo4.Text) & _"'" & Trim$(Text1.Text) & "'" & " " & "And" & " " & Combo2.Text _ & " " & Trim$(Combo5.Text) & "'" & Text2.Text & "'" & " " & "And" _& " " & Combo3.Text & " " & Trim(Combo6.Text) & "'" & Trim(Text3.Text) & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo3.SetFocus
Text3.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
End If
'第一个组合关系为“与”，第二个组合关系为“或”
If Combo7.Text = "与" And Combo8.Text = "或" Then
txtSQL = txtSQL &Combo1.Text & " " & Trim$(Combo4.Text) & "'" & _
Trim$(Text1.Text) & "'" & " " & "And" & " " &Combo2.Text & _
" " & Trim$(Combo5.Text) & "'" & Text2.Text & "'" & " " & "or" & " " & _
Combo3.Text & " " & Trim(Combo6.Text) & "'" & Trim(Text3.Text) & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo3.SetFocus
Text3.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
End If
'第一个组合关系为“或”，第二个组合关系为“与”
If Combo7.Text = "或" And Combo8.Text = "与" Then
txtSQL = txtSQL &Combo1.Text& " " & Trim$(Combo4.Text) & "'" _
& Trim$(Text1.Text) & "'" & " " & "or" & " " & Combo2.Text_
& " " & Trim$(Combo5.Text) & "'" & Text2.Text & "'" & " " & "and" & " " _
& Combo3.Text & " " & Trim(Combo6.Text) & "'" & Trim(Text3.Text) & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo3.SetFocus
Text3.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
End If
'第一个组合关系为“或”，第二个组合关系为“或”
If Combo7.Text = "或" And Combo8.Text = "与" Then
txtSQL = txtSQL & Combo1.Text & " " & Trim$(Combo4.Text) & "'" _
& Trim$(Text1.Text) & "'" & " " & "or" & " " & Combo2.Text _
& " " & Trim$(Combo5.Text) & "'" & Text2.Text & "'" & " " & "or" & " " _
& Combo3.Text & " " & Trim(Combo6.Text) & "'" & Trim(Text3.Text) & "'"
Set mrc = ExecuteSQL(txtSQL, Msgtext)
If mrc.EOF Then '数据库中无记录时
MsgBox "无此记录", vbOKOnly + vbExclamation, "警告！"
Combo3.SetFocus
Text3.Text = ""
mygrid1.Clear
Exit Sub
Else
With mygrid1
.Rows = 2
.CellAlignment = 4
.TextMatrix(1, 0) = "教师"
.TextMatrix(1, 1) = "注册日期"
.TextMatrix(1, 2) = "注册时间"
.TextMatrix(1, 3) = "注销日期"
.TextMatrix(1, 4) = "注销时间"
.TextMatrix(1, 5) = "机器名"
Do While Not mrc.EOF
.Rows = .Rows + 1
.CellAlignment = 4
.TextMatrix(.Rows - 1, 0) = Trim$(mrc.Fields("UserID"))
.TextMatrix(.Rows - 1, 1) = Trim$(mrc.Fields("LoginDate"))
.TextMatrix(.Rows - 1, 2) = Trim$(mrc.Fields("LoginTime"))
.TextMatrix(.Rows - 1, 3) = Trim$(Format(mrc.Fields("LogoutDate")))
.TextMatrix(.Rows - 1, 4) = Trim$(Format(mrc.Fields("LogoutTime")))
.TextMatrix(.Rows - 1, 5) = Trim$(mrc.Fields("computer"))
mrc.MoveNext
Loop
End With
mrc.Close
End If
End If
Set mrc = Nothing '释放记录集
End If
End If