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mysqli_result::fetch_field

mysqli_fetch_field

(PHP 5, PHP 7, PHP 8)

mysqli_result::fetch_field -- mysqli_fetch_fieldRetourne le prochain champs dans le jeu de résultats

Description

Style orienté objet

public mysqli_result::fetch_field(): object|false

Style procédural

mysqli_fetch_field(mysqli_result $result): object|false

Retourne les attributs de la prochaine colonne dans le jeu de résultats représenté par le paramètre result en tant qu'objet. Appelez cette fonction de façon répétitive pour récupérer les informations de toutes les colonnes.

Liste de paramètres

result

Style procédural uniquement : Un objet mysqli_result retourné par mysqli_query(), mysqli_store_result(), mysqli_use_result(), ou mysqli_stmt_get_result().

Valeurs de retour

Retourne un objet qui contient les informations d'un champ ou false si aucune information n'est disponible pour ce champs.

Propriétés de l'objet
Propriété Description
name Le nom de la colonne
orgname Le nom original de la colonne si un alias a été spécifié
table Le nom de la table à laquelle ce champ appartient (s'il n'a pas été calculé)
orgtable Le nom original de la table si un alias a été spécifié
def Inutilisé. Toujours une chaîne vide
db Le nom de la base de données
catalog Inutilisé. Toujours "def"
max_length La longueur maximale du champ pour le jeu de résultats. À partir de PHP 8.1, cette valeur est toujours 0.
length La largeur du champ en octets. Pour les colonnes de type chaîne de caractères, la valeur de longueur varie en fonction du jeu de caractères de la connexion. Par exemple, si le jeu de caractères est latin1, un jeu de caractères mono-octet, la valeur de longueur pour une requête SELECT 'abc' est 3. Si le jeu de caractères est utf8mb4, un jeu de caractères multioctets dans lequel les caractères occupent jusqu'à 4 octets, la valeur de longueur est 12.
charsetnr Le numéro du jeu de caractères pour ce champs
flags Un entier représentant le bit-flags pour ce champs
type Le type de données utilisées pour ce champs
decimals Le nombre de décimales pour les champs numériques et la précision des secondes fractionnaires pour les champs temporels.

Exemples

Exemple #1 Style orienté objet

<?php
$mysqli
= new mysqli("localhost", "my_user", "my_password", "world");

/* Vérification de la connexion */
if (mysqli_connect_errno()) {
printf("Échec de la connexion : %s\n", mysqli_connect_error());
exit();
}

$query = "SELECT Name, SurfaceArea from Country ORDER BY Code LIMIT 5";

if (
$result = $mysqli->query($query)) {

/* Récupère les informations d'un champ pour toutes les colonnes */
while ($finfo = $result->fetch_field()) {

printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n\n", $finfo->type);
}
$result->close();
}

/* Fermeture de la connexion */
$mysqli->close();
?>

Exemple #2 Style procédural

<?php
$link
= mysqli_connect("localhost", "my_user", "my_password", "world");

/* Vérification de la connexion */
if (mysqli_connect_errno()) {
printf("Échec de la connexion : %s\n", mysqli_connect_error());
exit();
}

$query = "SELECT Name, SurfaceArea from Country ORDER BY Code LIMIT 5";

if (
$result = mysqli_query($link, $query)) {

/* Récupère les informations d'un champ pour toutes les colonnes */
while ($finfo = mysqli_fetch_field($result)) {

printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n\n", $finfo->type);
}
mysqli_free_result($result);
}

/* Fermeture de la connexion */
mysqli_close($link);
?>

Les exemples ci-dessus vont afficher :

Name:     Name
Table:    Country
max. Len: 11
Flags:    1
Type:     254

Name:     SurfaceArea
Table:    Country
max. Len: 10
Flags:    32769
Type:     4

Voir aussi

add a note

User Contributed Notes 8 notes

up
62
iansoko at hotmail dot com
13 years ago
here are the data types that correspond to the TYPE number returned by fetch_field.

thought i would post this here since i couldn't find the info elsewhere.

numerics
-------------
BIT: 16
TINYINT: 1
BOOL: 1
SMALLINT: 2
MEDIUMINT: 9
INTEGER: 3
BIGINT: 8
SERIAL: 8
FLOAT: 4
DOUBLE: 5
DECIMAL: 246
NUMERIC: 246
FIXED: 246

dates
------------
DATE: 10
DATETIME: 12
TIMESTAMP: 7
TIME: 11
YEAR: 13

strings & binary
------------
CHAR: 254
VARCHAR: 253
ENUM: 254
SET: 254
BINARY: 254
VARBINARY: 253
TINYBLOB: 252
BLOB: 252
MEDIUMBLOB: 252
TINYTEXT: 252
TEXT: 252
MEDIUMTEXT: 252
LONGTEXT: 252
up
5
Anonymous
12 years ago
The constants for the TYPE number returned by fetch_field are enumerated here (MYSQLI_TYPE_*):
http://php.net/manual/en/mysqli.constants.php
up
13
ragtag at hotmail dot com
16 years ago
The flags used by MySql are:
NOT_NULL_FLAG = 1
PRI_KEY_FLAG = 2
UNIQUE_KEY_FLAG = 4
BLOB_FLAG = 16
UNSIGNED_FLAG = 32
ZEROFILL_FLAG = 64
BINARY_FLAG = 128
ENUM_FLAG = 256
AUTO_INCREMENT_FLAG = 512
TIMESTAMP_FLAG = 1024
SET_FLAG = 2048
NUM_FLAG = 32768
PART_KEY_FLAG = 16384
GROUP_FLAG = 32768
UNIQUE_FLAG = 65536

To test if a flag is set you can use & like so:
<?php
$meta
= $mysqli_result_object->fetch_field();
if (
$meta->flags & 4) {
echo
'Unique key flag is set';
}
?>
up
2
andre at koethur dot de
10 years ago
Here are two methods for converting the 'type' and 'flags' attributes to text for debugging purposes. They both use the predefined MYSQLI_ constants to generate the text.

<?php

public static function h_type2txt($type_id)
{
static
$types;

if (!isset(
$types))
{
$types = array();
$constants = get_defined_constants(true);
foreach (
$constants['mysqli'] as $c => $n) if (preg_match('/^MYSQLI_TYPE_(.*)/', $c, $m)) $types[$n] = $m[1];
}

return
array_key_exists($type_id, $types)? $types[$type_id] : NULL;
}

public static function
h_flags2txt($flags_num)
{
static
$flags;

if (!isset(
$flags))
{
$flags = array();
$constants = get_defined_constants(true);
foreach (
$constants['mysqli'] as $c => $n) if (preg_match('/MYSQLI_(.*)_FLAG$/', $c, $m)) if (!array_key_exists($n, $flags)) $flags[$n] = $m[1];
}

$result = array();
foreach (
$flags as $n => $t) if ($flags_num & $n) $result[] = $t;
return
implode(' ', $result);
}

?>
up
1
sofe2038 at gmail dot com
6 years ago
The constants in a few other comments above appear to be inaccurate. Here are some more official references that seem quite hard to search.

The "type" attribute: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-type
The "flags" attribute: https://github.com/google/mysql/blob/master/include/mysql_com.h#L133

In addition, all attributes are explained on the COM_QUERY_RESPONSE page too: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition
up
1
rvila at revolutionvisualarts dot com
8 years ago
The predefined constant values returned by the function get_predefined_constants() for:

MYSQLI_TYPE_CHAR = 1
MYSQLI _TYPE_TINYINT = 1

If the code is used to categorized the type of field use this values will of course create confusion. For example:

if($fieldtype === "CHAR"){
$field_html_attribute = "text";
$field_html_length = 1;
} elseif($fieldtype === "TINYINT") {
$field_html_attribute = "number";
$field_html_length = 1;
}

If an array is created to set the key as the numeric value and the value of that key as the the text title, TINYINT will be replaced by CHAR value. But is this process is reversed, then the code will select TINYINT if the foreach statement set to break when the numeric value of the flag equals the value of the current key as the first intance.

Base in the note added by Johnathan at http://php.net/manual/en/mysqli.field-count.php the values should be:

CHAR = 254
TINYINT = 1

But predefined function attributes the value 254 to MYSQLI_TYPE_STRING.

Just for FYI
up
0
nick
7 years ago
It is not possible to get the values for an enum or set field through fetch_fields(). As far as I can tell this is because it hasn't been implemented in the mysqlnd api but whatever the reason it is not possible and you must issue a query like SHOW COLUMNS directly and interrogate the result to determine them.

Incidentally you need to check the enum_flag rather than look for the enum_type to determine whether a field is enum or not. The type returned is usually some kind of string.
up
2
miqrogroove at gmail dot com
11 years ago
Beware the values of the predefined constants. They do not always correlate with the actual field types. For example:

MYSQLI_TYPE_BLOB: 252
MYSQLI_TYPE_TINY_BLOB: 249
MYSQLI_TYPE_MEDIUM_BLOB: 250
MYSQLI_TYPE_LONG_BLOB: 251

MySQLi will indeed return a value of 252 for a tinytext field, but as you can see, this does not correspond to the value of MYSQLI_TYPE_TINY_BLOB.
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