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mysql_num_fields

(PHP 4, PHP 5)

mysql_num_fieldsRetourne le nombre de champs d'un résultat MySQL

Avertissement

Cette extension était obsolète en PHP 5.5.0, et a été supprimée en PHP 7.0.0. À la place, vous pouvez utiliser l'extension MySQLi ou l'extension PDO_MySQL. Voir aussi MySQL : choisir une API du guide. Alternatives à cette fonction :

Description

mysql_num_fields(resource $result): int|false

Retourne le nombre de champs d'une requête.

Liste de paramètres

result

La ressource de résultat qui vient d'être évaluée. Ce résultat vient de l'appel à la fonction mysql_query().

Valeurs de retour

Retourne le nombre de champs d'un jeu de résultat en cas de succès ou false si une erreur survient.

Exemples

Exemple #1 Exemple avec mysql_num_fields()

<?php
$result
= mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!
$result) {
echo
'Impossible d\'exécuter la requête : ' . mysql_error();
exit;
}

/* Retourne 2 car id,email === 2 champs */
echo mysql_num_fields($result);
?>

Notes

Note:

Pour des raisons de compatibilité ascendante, l'alias obsolète suivant peut être utilisé : mysql_numfields()

Voir aussi

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User Contributed Notes 5 notes

up
0
php at jezusisheer dot nl
16 years ago
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.
up
-2
matt at iwdt dot net
22 years ago
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
up
-6
tharkey at tharkey dot net
20 years ago
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 (' / ');
}
up
-5
bwark at stanford dot edu
23 years ago
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.
up
-12
apass AT passmoore DOT com
21 years ago
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.
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