如何给DataEnvironment1的属性赋值

Private Sub Command2_Click()
Dim a As String, b As Long, c As Long, sql As String, mlink As String
a = Text1.Text
b = Text3.Text
c = Text4.Text
sql = "select 姓名 ,产品 ,count(产品) as 数量 ,价格 ,sum(价格) as 合计 from kc " _
& " where 姓名= ' " & a & " ' and 时间 > = " & b & " and 时间 <= " & c & " group by 姓名,产品,价格 "

DataEnvironment1.Connection1.ConnectionString =sql

End Sub
程序执行到倒数第2句的时候出错了，原因是对象关闭的时候不允许操作。
不知道有什么办法可以解决，而且要保留sql中的变量


[解决办法]
Set DataEnvironment1 = Nothing
DataEnvironment1.Connection1= strCnn （数据库链接代码）

sql语句应该在下面的COMMAND中调用
DataEnvironment1.Commands("gas_money").CommandText = "SELECT * FROM ChargeArre WHERE ........"