（宾馆管理系统）Visual Basic 数据库开发典型模块与实例精讲.pdf

文档介绍：宾馆管理系统第 9 章
Public Function FieldAtoFieldB(ByVal TableName As String, ByVal FieldB As
String, ByVal FieldA As String, ByVal vFieldA As String) As String
On Error GoTo ErrHandle
FieldAtoFieldB = ""
Dim m_rst As New
With m_rst
Set .ActiveConnection = g_ADOConn
.Open "select " & FieldB & " from " & TableName & " where " & FieldA
& "='" & vFieldA & "'"
If .RecordCount > 0 Then
.MoveFirst
FieldAtoFieldB = IIf(IsNull(.Fields(FieldB).value), Empty,.Fields
(FieldB).value)
End If
.Close
End With
Exit Function
ErrHandle:
ShowError "modFunction", "FieldAtoFieldB", ,
End Function
getMaxId
本函数输入数据库表名,根据表名,构造 SQL 语句,查询出指定表中 ID 字段的最大
值,代码如下。
Public Function getMaxId(ByVal strTable As String) As Integer
On Error GoTo ErrorHandle
Dim rstQry As
Dim strSQL As String
getMaxId = 0
Set rstQry = New
strSQL = " SELECT MAX(ID) AS ID FROM " & strTable
strSQL, g_ADOConn, adOpenStatic, adLockReadOnly
getMaxId = ("ID")
Set rstQry = Nothing
Exit Function
ErrorHandle:
Set rstQry = Nothing
ShowError "monFunction", "getMaxId", ,
End Function
searchbySql
该函数输入 SQL 语句,根据 SQL 语句查询数据库,并返回结果记录集。
Public Function searchbySql(ByVal strSQL As String) As
On Error GoTo ErrorHandle
Dim rstGet As New
strSQL, g_ADOConn, adOpenDynamic, adLockOptimistic
491
VB Visual Basic 数据库开发典型模块与实例精讲
Set searchbySql = rstGet
Exit Function
ErrorHandle:
Set rstGet = Nothing
ShowError "monFunction", "searchbySql", ,
End Function


多学两招

当对数据库访问很频繁,数据量又很大的时候,同数据库的交互将成为影响处理
速度的瓶颈,因为这些交互都将受 I/O 资源和网络性能的影响。此时,在数据库中编
写存储过程,将大量的处理放在数据库内部,从而减少访问数据库的次数,将是很好
的选择。

创建公共模块 modMain
添加一个公用模块,并命名为 modMain,作为整个工程的入口。modMain 模块包含一
个 main()主过程,作为整个应用程序的开始。Main()中设置并