PHP Unconference Europe 2015

mysql_num_fields

(PHP 4, PHP 5)

mysql_num_fieldsSonuçtaki alan sayısını al

Açıklama

int mysql_num_fields ( resource $sonuç )

Bir sorgunun döndürdüğü alanların sayısını alır.

Değiştirgeler

sonuç

resource türünde sorgu sonucu. Bu sonuç bir mysql_query() çağrısının sonucudur.

Dönen Değerler

Başarı durumunda resource türündeki sonuç kümesinde bulunan alanların sayısını, hata durumunda FALSE döndürür.

Örnekler

Örnek 1 - mysql_num_fields() örneği

<?php
$result 
mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!
$result) {
    echo 
'Sorgu çalıştırılamadı: ' mysql_error();
    exit;
}

/* 2 döndürür, çünkü id,email === iki alan */
echo mysql_num_fields($result);
?>

Notlar

Bilginize:

Geriye uyumluluk adına, kullanımı önerilmese de şu takma adı kullanabilirsiniz: mysql_numfields()

Ayrıca Bakınız

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User Contributed Notes 5 notes

up
0
tharkey at tharkey dot net
11 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
0
matt at iwdt dot net
13 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
-1
bwark at stanford dot edu
13 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
-1
php at jezusisheer dot nl
7 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
-1
apass AT passmoore DOT com
12 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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