我们在写ASP数据库程序的时候，通常都会用到SQL语句，而在增加数据和更新数据的时候，通常会使用一下方式：insert into message (incept,sender,title,content,sendtime,flag,issend) values ('"&incept(i)&"','"&membername&"','"&title&"','"&message&"',Now(),0,1)当字段比较多的时候，而且更新的表比较多的时候，修改起来会比较麻烦，而且查找错误也比较困难。使用这个SQL类后可以简化修改，而且查错也比较容易。通过类的AddField函数增加字段名和字段值，可轻松的将字段名和字段值插入SQL语句，然后返回该SQL语句。
下面让我们看看这个类的代码：
<%
class SQLString
'************************************
'变量定义
'************************************
'sTableName ---- 表名
'iSQLType ----SQL语句类型：0-增加，1-更新，2-删除,3-查询
'sWhere ---- 条件
'sOrder ---- 排序方式
'sSQL ----值
Private sTableName,iSQLType,sWhere,sOrder,sSQL
'************************************
'类初始化/结束
'************************************
Private Sub Class_Initialize()
sTableName=""
iSQLType=0
sWhere=""
sOrder=""
sSQL=""
End Sub
Private Sub Class_Terminate()
End Sub
'************************************
'属性
'************************************
‘设置表名的属性
Public Property Let TableName(value)
sTableName=value
End Property
‘设置条件
Public Property Let Where(value)
sWhere=value
End Property
‘设置排序方式
Public Property Let Order(value)
sOrder=value
End Property
‘设置查询语句的类型
Public property Let SQLType(value)
iSQLType=value
select case iSQLType
case 0
sSQL="insert into #0 (#1) values (#2)"
case 1
sSQL="update #0 set #1=#2"
case 2
sSQL="delete from #0 "
case 3
sSQL="select #1 from #0 "
end select
End Property
'************************************
'函数
'************************************
'增加字段（字段名称，字段值）
Public Sub AddField(sFieldName,sValue)
select case iSQLType
case 0
sSQL=replace(sSQL,"#1",sFieldName & ",#1")
sSQL=replace(sSQL,"#2","'" & sFieldName & "',#2")
case 1
sSQL=replace(sSQL,"#1",sFieldName)
sSQL=replace(sSQL,"#2","'" & sFieldName & "',#1=#2")
case 3
sSQL=replace(sSQL,"#1",sFieldName & ",#1")
End Select
End Sub
'返回SQL语句
Public Function ReturnSQL()
sSQL=replace(sSQL,"#0",sTableName)
select case iSQLType
case 0
sSQL=replace(sSQL,",#1","")
sSQL=replace(sSQL,",#2","")
case 1
sSQL=replace(sSQL,",#1=#2","")
case 3
sSQL=replace(sSQL,",#1","")
end Select
if sWhere<>"" then
sSQL=sSQL & " where " & sWhere
end if
if sOrder<>"" then
sSQL=sSQL & " order by " & sOrder
end if
ReturnSQL=sSQL
End Function
'清空语句
Public Sub Clear()
sTableName=""
iSQLType=0
sWhere=""
sOrder=""
sSQL=""
End Sub
end class
%>
使用方法：
例句：insert into message (incept,sender,title,content,sendtime,flag,issend) values ('"&incept(i)&"','"&membername&"','"&title&"','"&message&"',Now(),0,1)
set a =new SQLString ‘创建类对象
a.TableName=" message " ‘设置表名为message
a.SQLType=0 ‘设置查询类型为增加记录
a.AddField " incept", incept(i)
a.AddField " sender ", membername
a.AddField " title ", membername
a.AddField " sender ", title
a.AddField " content ", message
a.AddField " sendtime ", sendtime()
a.AddField " flag", 0
a.AddField " issend ", 1
Response.Write a.ReturnSQl
set a=nothing