在VB中如何查询数据库最早时间并且赋值给日期变量？我的数据库时间类型是文本的，初学，请教一下，谢谢！

Dim cnnmdb As ADODB.Connection
Dim a As Date
Dim b As Date
Set cnnmdb = New ADODB.Connection
cnnmdb.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\110.mdb;Persist Security Info=False"

a = cnnmdb.Execute("select top 1 from sheet1 order by CDate(T) desc")
b = cnnmdb.Execute("select top 1 from sheet1 order by CDate(T) asc")

Dim cnnmdb As ADODB.Connection
dim rs1 as recordset
Dim a As Date
Dim b As Date
Set cnnmdb = New ADODB.Connection
cnnmdb.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\110.mdb;Persist Security Info=False"
set rs1=cnnmdb.Execute("select top 1 * from sheet1 order by CDate(T) desc")
a =CDate( rs1("日期字段名"))
set rs1 = cnnmdb.Execute("select top 1* from sheet1 order by CDate(T) asc")
b =CDate( rs1("日期字段名"))

'定义变量 dim access as new adodb.connection dim res as new adodb.recordset '连接数据库 access.connectionstring = "provider=microsoft.jet.oledb.4.0;" _                + " data source=" + app.path + "\test.mdb; "  res.open "select * from test  where  学号 = ‘001’", access, 1, 3 '取表中字段test  num=res.fields (test)