Try
Dim a As String
Dim c As String
Dim b As String
Dim str As String
Try
Select Case (lx.SelectedValue)
Case 0
b = "*"
Case 1
b = ""
Case 2
b = ""
Case 3
b = ""
End Select
c = zi.Text
If (b = "*") Then
DataBind()
Else
Session("sqlstr") = "select * from message1 where " + b + " like '%" + c + "%'"
DataBind()
End If
Catch ex As Exception

End Try

Catch ex As Exception

End Try