mysql_num_fields

(PHP 4, PHP 5)

mysql_num_fields — Get number of fields in result

Описание

int mysql_num_fields ( resource $result )

Retrieves the number of fields from a query.

Параметри

result: Резултатният ресурс, който бива оценен. Този резултат идва от извикване на mysql_query().

Връщани стойности

Returns the number of fields in the result set resource on success, or FALSE on failure.

Примери

Example #1 A mysql_num_fields() example


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

/* returns 2 because id,email === two fields */
echo mysql_num_fields($result);
?>

Бележки

Забележка: От съображения за обратна съвместимост, може да бъде използван следният непрепоръчителен псевдоним: mysql_numfields()

Вж. също

mysql_select_db() - Избира MySQL база от данни
mysql_query() - Изпраща заявка към MySQL
mysql_fetch_field() - Get column information from a result and return as an object
mysql_num_rows() - Връща броя на редовете в указаното множество с резултати

mysql_num_rows

mysql_list_tables

[edit] Last updated: Fri, 18 Sep 2009

add a note User Contributed Notes mysql_num_fields - [5 notes]

down

php at jezusisheer dot nl ¶

6 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.

down

tharkey at tharkey dot net ¶

9 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 (' / ');

                        }

down

apass AT passmoore DOT com ¶

10 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.

down

matt at iwdt dot net ¶

11 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

down

bwark at stanford dot edu ¶

12 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.

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