我的语句：
Dim conn As System.Data.OleDb.OleDbConnection
Dim sStr As String
Dim dr As System.Data.OleDb.OleDbDataReader
？？？？？？？

sStr = "Provider=MSDAORA.1;pwd=pwd;user id=username;datas ource=kksb"
conn = New System.Data.OleDb.OleDbConnection(sStr)
conn.Open()
sStr = "select * from t_user where username='" & username.Text & "' and pwd='" & pwd.text & "'"
问号部分不会

谢谢大家的帮助
原来是需要OleDbCommand就可以了
我已经搞定了！