mysql_num_fields

(PHP 4, PHP 5)

mysql_num_fields — Liefert die Anzahl der Felder in einem Ergebnis

Beschreibung

int mysql_num_fields ( resource $Ergebnis-Kennung )

mysql_num_fields() liefert die Anzahl der Felder in der Ergebnismenge, die mit dem Parameter Ergebnis-Kennung angegeben wurde.

Beispiel #1 Ein mysql_num_fields() Beispiel


<?php
$result = mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!$result) {
    echo 'Abfrage konnte nicht ausgeführt werden: ' . mysql_error();
    exit;
}

/* Gibt 2 zurück, weil id,email === zwei Felder */
echo mysql_num_fields($result);
?>

Für Abwärtskompatibilität kann mysql_numfields() verwendet werden. Diese Funktion ist jedoch veraltet.

Siehe auch mysql_select_db(), mysql_query(), mysql_fetch_field() und mysql_num_rows().

5 BenutzerBeiträge:
- Beiträge aktualisieren...

php at jezusisheer dot nl
30.03.2007 9:10


Note that, if you want to get the amount of columns of a table and you're using the "SHOW COLUMNS FROM $table" query, you will have to use mysql_num_rows() instead of mysql_num_fields() on the result. This becomes logical when thinking about it, because the SHOW COLUMNS query returns a result with six columns (Field, Type, Null, Key, Default and Extra) and with a single row for every column found. If you'd count the number of fields, you'd always get 6. If you count the number of rows, you'll get the amount of columns found.

tharkey at tharkey dot net
19.06.2003 20:26


You can use it without a requete, just to list the fields :



$liste_champs = mysql_list_fields ( $Base, $Table, $connexion);



for ($i=0; $i < mysql_num_fields ($l_champs); $i++) {

                        echo ( mysql_field_name ($l_champs, $i) );

                        echo (' / ');

                        }

apass AT passmoore DOT com
2.10.2002 0:52


Adding to the last comment: you can dynamically loop through any number of  columns AND rows like so-



$query="your SQL";

$result=mysql_query($query) or die("Query ($query) sucks!");

$fields=mysql_num_fields($result);



echo "<table>\n<tr>";

for ($i=0; $i < mysql_num_fields($result); $i++) //Table Header

{ print "<th>".mysql_field_name($result, $i)."</th>"; }

echo "</tr>\n";

while ($row = mysql_fetch_row($result)) { //Table body

echo "<tr>";

    for ($f=0; $f < $fields; $f++) {

    echo "<td>$row[$f]</td>"; }

echo "</tr>\n";}

echo "</table><p>";



This has been tested.

matt at iwdt dot net
24.09.2001 3:09


here's one way to print out a row of <th> tags from a table


NOTE: i didn't test this





$result = mysql_query("select * from table");





for ($i = 0; $i < mysql_num_fields($result); $i++) {


    print "<th>".mysql_field_name($result, $i)."</th>\n";


}





post a comment if there's an error

bwark at stanford dot edu
24.12.2000 11:56


If you just want the number of fields in a table, you can do something like this:





<?php


$db_id = mysql_connet();


$result = mysql_query("DESCRIBE [tableName], $db_id);





$numFields = mysql_num_rows($result);


?>





Because "DESCRIBE" returns one row for each field in the table (at least in MySQL), this will work.

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mysql_num_fields

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