Read Excel .xlsx file and return first worksheet as a DataTable

read_xlsx.cs

using System.Data;
using System.Data.OleDb;
using System.Diagnostics;

namespace JW4.DB.Util
{
	public static class Excel
	{
		public static DataTable GetFirstWorksheetAsTable(string filename)
		{
			var ds = new DataSet();
			using (var conn = new OleDbConnection(string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=\"Excel 12.0 Xml;HDR=YES;IMEX=1\";", filename)))
			{
				conn.Open();
				var worksheets = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] {null, null, null, "Table"});
				Debug.Assert(worksheets != null, "worksheets != null");
				var firstsheet = worksheets.Rows[0][2].ToString();
				var query = string.Format("SELECT * FROM [{0}]", firstsheet);
				var adapter = new OleDbDataAdapter(query, conn);
				adapter.Fill(ds);
			}
			var table = ds.Tables[0];
			return table;
		}
	}
}