多个mysql表，其中...和

Question

Can I somehow compare 3 tables with this?

I get this error:

mysql_free_result() expects parameter 1 to be resource

$duom=mysql_query("SELECT * from Pazymiai, Mokinys, Mokymo_dalykas where Pazymiai.Mokinio_Nr = Mokinys.Nr AND Pazymiai.Dalyko_Nr = Mokymo_Dalykas.Nr;");
    while ($result = mysql_fetch_array ($duom)) {
        echo("
            <tr>
            <td>$result[6]</td>
            ...
            </tr>");
    }
    mysql_free_result($duom);
    mysql_close();

Answer 1

Here is your SQL using a join . This work?

SELECT * from Pazymiai as p
join Mokinys as m
on p.Mokinio_Nr = m.Nr
join Mokymo_dalykas as md
on p.Dalyko_Nr = md.Nr

Documentation link: http://dev.mysql.com/doc/refman/5.0/en/join.html