mysql_query如何循环直到结果？

Question

I have a table of nested product categories. I want to get data from field custom_inserts_ru and if it's empty - go to top (parent category) and check again.

$mycat = 1146;
$result = mysql_query("SELECT categoryID, parent, custom_inserts_ru FROM SC_categories WHERE categoryID=$mycat");
while($row = mysql_fetch_row($result)) {
    if($row[2]==''){
        $mycat = $row[1];
    } else {
        echo "$row[1] <pre>$row[2]</pre>";
    }
}

I try this, but don't work(

Answer 1

I would do it like this

function get_inserts ($db, $id) {
    $base_sql = "SELECT c.categoryID, 
           c.parent, 
           IFNULL(c.custom_inserts_ru, p.custom_inserts_ru) custom_inserts_ru, 
           p.parent parent_parent
      FROM SC_categories c LEFT JOIN
           SC_categories p ON c.parent = p.categoryID
     WHERE c.categoryID=";

    $inserts = "";
    do {
        $result = mysql_query ($base_sql . $id, $db);
        if (!$result) break;
        $row = mysql_fetch_assoc($result);
        $inserts = $row['custom_inserts_ru'];
        $id = $row['parent_parent'];

    } while (strlen($inserts) == 0 && $id);

    if($result) {
        mysql_free_result ($result);
    }
    return $inserts;
 } 

To lessen the number of subsequent queries for a deep tree of categories a self join is introduced which fetches value of custom_inserts_ru either from current category or from its immediate parent in one select.

To use it

$mycat = 1146;
$db = mysql_connect(...);
if (!$db) {
    die('Not connected : ' . mysql_error());
}
$db_selected = mysql_select_db('test', $db);
if (!$db_selected) {
    die ('Unable to select database : ' . mysql_error());
}

$inserts = get_inserts($db, $mycat);
echo "custom_inserts_ru for Id $currentID is '$inserts'";
mysql_close($db);

Since mysql_* extension is deprecated , you better switch to PDO or MySQLi and use prepared statements .

Answer 2

无论如何，您真的根本没有搜索过任何东西，就像最基本的东西一样：

while ($row = mysql_fetch_row($result)) {
//In a cycle
}