mysql_num_fields

(PHP 4, PHP 5, PECL mysql:1.0)

mysql_num_fields — 結果におけるフィールドの数を得る

説明

int mysql_num_fields ( resource $result )

クエリから、フィールドの数を取得します。

パラメータ

result: 評価された結果リソース。この結果は、mysql_query() のコールにより得られたものです。

返り値

成功した場合に結果セット resource のフィールド数、失敗した場合に FALSE を返します。

例

例1 mysql_num_fields() の例


<?php
$result = mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!$result) {
    echo 'Could not run query: ' . mysql_error();
    exit;
}

/* id,email の 2 つのフィールドがあるので、2 を返す */
echo mysql_num_fields($result);
?>

注意

注意: 下位互換のために、次の非推奨別名を使用してもいいでしょう。 mysql_numfields()

参考

mysql_num_rows

mysql_list_tables

Last updated: Fri, 18 Jul 2008

add a note User Contributed Notes
mysql_num_fields

php at jezusisheer dot nl
30-Mar-2007 12:10


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-Jun-2003 11:26


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
01-Oct-2002 03:52


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
23-Sep-2001 06:09


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-Dec-2000 02:56


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.

add a note

mysql_num_rows

mysql_list_tables

Last updated: Fri, 18 Jul 2008