open System
        open System.Data
        open System.Data.OleDb
        open System.Console


        let connstr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\usr\\my_db.mdb;UserId=admin;Password=;"
        let dbconn = new OleDbConnection(connstr);; 
        do dbconn.Open() 
        let sql_command= new OleDbCommand("select perf from perfs where id = 1",dbconn)
        let sql_stream : Collections.Generic.IEnumerable<System.Data.Common.DbDataRecord>  =
                sql_command.ExecuteReader(CommandBehavior.CloseConnection) |>                                         IEnumerable.untyped_to_typed ;;
        let sql_output = sql_stream  |> IEnumerable.map (fun x -> x.GetDouble 0 )
                |> IEnumerable.to_array;;
        print_any sql_output;

Useful, as OleDb can connect to most kinds of databases.