Suppose you want to export the whole data in one table from sql server 2008 directly using vb.net to EXCEL? You can use the following code -
Dim dt As DataTable = GetData()
Dim attachment As String = "attachment; filename=Employee.xls"
Response.ClearContent()
Response.AddHeader("content-disposition", attachment)
Response.ContentType = "application/vnd.ms-excel"
Dim tab As String = ""
For Each dc As DataColumn In dt.Columns
Response.Write(tab + dc.ColumnName)
tab = vbTab
Next
Response.Write(vbLf)
Dim i As Integer
For Each dr As DataRow In dt.Rows
tab = ""
For i = 0 To dt.Columns.Count - 1
Response.Write(tab & dr(i).ToString())
tab = vbTab
Next
Response.Write(vbLf)
Next
Response.End()
Source: http://stackoverflow.com/questions/5621577/export-from-sql-server-to-excel-file-using-asp-net-and-vb-net
