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mysql_num_fields

(PHP 4, PHP 5)

mysql_num_fieldsObtém o numero de campos em um resultado

Descrição

int mysql_num_fields ( resource $result )

Obtém o numero de campos de uma consulta.

Parâmetros

result

The result resource that is being evaluated. This result comes from a call to mysql_query().

Valor Retornado

Retorna o numero de capos em um conjunto de resultados resource em caso de sucesso, ou FALSE em caso de falha.

Exemplos

Exemplo #1 Exemplo mysql_num_fields()

<?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);
?>

Notas

Nota:

Para compatibilidade com versões anteriores, o seguinte apelido obsoleto pode ser usado: mysql_numfields()

Veja Também

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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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