解决一个.NET联接SQL的问题

Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlClient.SqlException
Public Class connect
Private s As String
Private s1 As String
Public Connect As New SqlConnection("server=Yiyang;database=KDERP;uid=sa;password=123")
Sub New()
Connect.Open()
End Sub
Public Property sql()
Get
Return s
End Get
Set(ByVal Value)
s = Value
End Set
End Property
'Public Property table()
' Get
' Return s1
' End Get
' Set(ByVal Value)
' s1 = Value

'End Property
Public Function Retable() As DataTable

Dim com As New DataSet()

Dim ada As New SqlDataAdapter()
Dim com1 As New SqlCommand()
com1.Connection = Connect
com1.CommandText = s
ada.SelectCommand = com1
ada.Fill(com, "t1")
Return com.Tables(0)

End Function
Public Function Exec() As Integer
Dim i As Integer

Dim com As New SqlCommand()
com.CommandText = s
com.Connection = Connect
i = com.ExecuteNonQuery()
Return i
End Function
Public Function Retdataset(ByVal t As String) As DataSet

Dim com As New SqlCommand()
com.Connection = Connect
com.CommandText = s
Dim ada As New SqlDataAdapter()
ada.SelectCommand = com
Dim da As New DataSet()
ada.Fill(da, t)
Return da
End Function
Public Function Retdataread() As SqlDataReader

Dim com As New SqlCommand()
com.Connection = Connect
com.CommandText = s
Return com.ExecuteReader
End Function
End Class