例如想在一个用户数据库中查询他的用户名和他的密码，但恰好该用户使用的名字和密码中有特殊的字符，例如单引号，“|”号，双引号或者连字符“&”。
例如他的名字是1'test，密码是A|&900，这时当你执行以下的查询语句时，肯定会报错：
SQL = "SELECT * FROM SecurityLevel WHERE UID='" & UserID & "'"
SQL = SQL & " AND PWD='" & Password & "'"
因为你的SQL将会是这样：
SELECT * FROM SecurityLevel WHERE UID='1'test'　AND PWD='A|&900'
在SQL中，"|"为分割字段用的，显然会出错了。现在提供下面的几个函数，专门用来处理这些头疼的东西：

Function ReplaceStr (TextIn, ByVal SearchStr As String, _
ByVal Replacement As String, _
ByVal CompMode As Integer)
Dim WorkText As String, Pointer As Integer
If IsNull(TextIn) Then
ReplaceStr = Null
Else
WorkText = TextIn
Pointer = InStr(1, WorkText, SearchStr, CompMode)
Do While Pointer > 0
WorkText = Left(WorkText, Pointer - 1) & Replacement & _
Mid(WorkText, Pointer + Len(SearchStr))
Pointer = InStr(Pointer + Len(Replacement), WorkText, _
SearchStr, CompMode)
Loop
ReplaceStr = WorkText
End If
End Function

Function SQLFixup(TextIn)
SQLFixup = ReplaceStr(TextIn, "'", "''", 0)
End Function

Function JetSQLFixup(TextIn)
Dim Temp
Temp = ReplaceStr(TextIn, "'", "''", 0)
JetSQLFixup = ReplaceStr(Temp, "|", "' & chr(124) & '", 0)
End Function

Function FindFirstFixup(TextIn)
Dim Temp
Temp = ReplaceStr(TextIn, "'", "' & chr(39) & '", 0)
FindFirstFixup = ReplaceStr(Temp, "|", "' & chr(124) & '", 0)
End Function
有了上面几个函数后，当你在执行一个sql前，请先使用：
SQL = "SELECT * FROM SecurityLevel WHERE UID='" & SQLFixup(UserID) & "'"
SQL = SQL & " AND PWD='" & SQLFixup(Password) & "'"