机房收费系统之常用语句
【前言】
机房收费系统在验收的时候，师父最后给我提了一个建议，希望我可以关于机房收费系统的常用语句总结一下，那些固定的语句以后也会经常会用到，总结一下对于以后的学习比较有利，自己也较有同感，因此写下这篇博客。
【正文】
一、对于数据库的增、删、改、查
<定义>：
<span style="font-size:18px;"> Dim mrc As ADODB.Recordset Dim txtSQL As String Dim Msgtext As String </span>
<增>：
<span style="font-size:18px;"> mrc.AddNew
With mrc
.Fields(1) = txtCardID.Text
.Fields(2) = txtSID.Text
.Fields(3) = txtName.Text
.Fields(4) = txtDepart.Text
.Fields(5) = txtSex.Text
.Fields(6) = txtOndate.Text
.Fields(7) = txtOntime.Text
.Fields(8) = txtOffdate.Text
.Fields(9) = txtOfftime.Text
.Fields(10) = txtContime.Text
.Fields(11) = Val(txtConsume.Text)
.Fields(12) = Val(txtCash.Text)
.Fields(13) = "正常下机"
.Fields(14) = Winsock1.LocalHostName
End With
mrc.Update</span>
<查>：
查询条件限制为1条：
<span style="font-size:18px;"> </span><span style="font-size:18px;">txtSQL = "select * from online_info where cardno='" & Trim(txtCardID.Text) & "'" Set mrc = ExecuteSQL(txtSQL, Msgtext)</span>
查询条件限制为多条：
<span style="font-size:18px;"> txtSQL = "select * from student_Info where cardno ='" & Trim(txtCardID.Text) & "'and status='" & "不使用" & "'" Set mrcStudent = ExecuteSQL(txtSQL, Msgtext)</span>
对于SQL数据库的一些操作经常会出现很多引号，容易出现错误，不明白如何将这些引号断开来看，下图是根据自己的理解来划分引号的位置（如果大家有不同的见解，希望我们可以讨论）：
二、对于MDI窗体及窗体上的图片，如何将子窗体在运行的时候显示
<定义API函数>：
<span style="font-size:18px;">Private Declare Function SetParent Lib "user32" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long </span>
<将窗体显示>：
<span style="font-size:18px;">SetParent frmReCashRecord.hWnd, Picture1.hWnd</span>
三、将数据库中的信息显示在MSFlexGrid1控件中
<span style="font-size:18px;">With MSFlexGrid1
.CellAlignment = 4
.Rows = 1
.TextMatrix(0, 0) = "用户名"
.TextMatrix(0, 1) = "姓名"
.TextMatrix(0, 2) = "开户人"
Do While mrc.EOF = False
.Rows = .Rows + 1
.TextMatrix(.Rows - 1, 0) = Trim(mrc.Fields(0))
.TextMatrix(.Rows - 1, 1) = Trim(mrc.Fields(3))
.TextMatrix(.Rows - 1, 2) = Trim(mrc.Fields(1))
mrc.MoveNext
Loop
End With</span>
四、对于MDI窗体，如何使在打开第二个窗体时将第一个窗体最小化在MDI窗体的左下端
<span style="font-size:18px;">Private Sub form_Activate()
Dim a As Form
For Each a In Forms
If a.Name <> frmMain.Name And a.Name <> Me.Name Then
a.WindowState = 1 '1为窗体最小化，0为正常，2为最大
Me.ZOrder 0 '日结账单窗体显示在MDI窗体的最前端
End If
Next
End Sub</span>
五、将MSFlexGrid控件中的信息导出到Excel表
<span style="font-size:18px;">Public Sub OutDataToExcel(Flex As MSFlexGrid) '导出至Excel表的过程
Dim s As String
Dim i As Integer
Dim j As Integer
Dim k As Integer
On Error GoTo ert
Me.MousePointer = 11
Dim Excelapp As Excel.Application
Set Excelapp = New Excel.Application
On Error Resume Next
DoEvents
Excelapp.SheetsInNewWorkbook = 1 '代表新插入工作表的个数
Excelapp.Workbooks.Add
Excelapp.ActivateSheet.Cells(1, 3) = s
Excelapp.Range("C1").Select
Excelapp.Selection.Font.FontStyle = "Bold"
Excelapp.Selection.Font.Size = 16
With Flex
k = .Rows
For i = 0 To k - 1
For j = 0 To .Cols - 1
DoEvents
Excelapp.ActivateSheet.Cells(3 + i, j + 1) = "'" & .TextMatrix(i, j)
Next j
Next i
End With
Me.MousePointer = 0
Excelapp.Visible = True
ert:
If Not (Excelapp Is Nothing) Then
Excelapp.Quit
End If
End Sub
Private Sub cmdExcel_Click()
OutDataToExcel MSFlexGrid1
End Sub</span>
六、关于选择日期的时候，出现起始和终止日期，设置温馨提示（不可晚于目前日期、终止日期不可小于起始日期）
<span style="font-size:18px;">Private Sub DTPicker1_change()
If DTPicker1.Value > Date Then
MsgBox "起始日期晚于目前日期，请验证", vbOKOnly + vbExclamation, "警告"
DTPicker1.Value = Date
End If
End Sub
Private Sub DTPicker2_change()
If DTPicker2.Value > Date Then
MsgBox "终止日期晚于目前日期，请验证", vbOKOnly + vbExclamation, "警告"
DTPicker2.Value = Date
End If
Dim a As Integer
a = DateDiff("d", DTPicker1.Value, DTPicker2.Value)
If a <= 0 Then
MsgBox "终止日期需晚于起始日期，请验证", vbOKOnly + vbExclamation, "警告"
Exit Sub
End If
End Sub</span>
【总结】
在总结的过程中，再次加深了对这些常用语句的印象。学习完后总结是必不可少的，这篇博客希望可以对大家有所帮助，在以后前进的道路上多回头看看。