mysqli_result::fetch_field_direct

    mysqli_fetch_field_direct

    (PHP 5, PHP 7, PHP 8)

    mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Obtiene los metadatos de un campo único

    Descripción

    Estilo orientado a objetos

    public mysqli_result::fetch_field_direct(int $index): object|false

    Estilo por procedimientos

    mysqli_fetch_field_direct(mysqli_result $result, int $index): object|false

    Devuelve un objeto que contiene los metadatos de un campo en el conjunto de resultados especificado.

    Parámetros

    result

    Sólo estilo por procedimientos: Un conjunto de identificadores de resultados devuelto por mysqli_query(), mysqli_store_result() o mysqli_use_result().

    index

    El número del campo. Este valor debe estar en el intervalo 0 a número de campos - 1.

    Valores devueltos

    Devuelve un objeto que contiene los metadatos de un campo o false si no se especifican metadatos para el campo index.

    Propiedades del objeto
    Propiedad Descripción
    name El nombre de la columna
    orgname El nombre original de la columna si se ha especificado un alias
    table El nombre de la tabla a la que pertenece este campo (si no ha sido calculado)
    orgtable El nombre original de la tabla si se ha especificado un alias
    def No utilizado. Siempre una string vacía
    db El nombre de la base de datos
    catalog No utilizado. Siempre "def"
    max_length La longitud máxima del campo para el conjunto de resultados. A partir de PHP 8.1, este valor es siempre 0.
    length El ancho del campo en bytes. Para las columnas de tipo string, el valor de longitud varía en función del juego de caracteres de la conexión. Por ejemplo, si el juego de caracteres es latin1, un juego de caracteres de un byte, el valor de longitud para una consulta SELECT 'abc' es 3. Si el juego de caracteres es utf8mb4, un juego de caracteres multibyte en el que los caracteres ocupan hasta 4 bytes, el valor de longitud es 12.
    charsetnr El número del juego de caracteres para este campo
    flags Un integer que representa los bit-flags para este campo
    type El tipo de datos utilizados para este campo
    decimals El número de decimales para los campos numéricos y la precisión de los segundos fraccionarios para los campos temporales.

    Ejemplos

    Ejemplo #1 Estilo orientado a objetos

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

    /* Verificación de la conexión */
    if (mysqli_connect_errno()) {
    printf("Fallo en la conexión: %s\n", mysqli_connect_error());
    exit();
    }

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

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

    /* Obtener información del campo para la columna 'SurfaceArea' */
    $finfo = $result->fetch_field_direct(1);

    printf("Nombre : %s\n", $finfo->name);
    printf("Tabla : %s\n", $finfo->table);
    printf("Tamaño máx : %d\n", $finfo->max_length);
    printf("Flags : %d\n", $finfo->flags);
    printf("Tipo : %d\n", $finfo->type);

    $result->close();
    }

    /* Cierre de la conexión */
    $mysqli->close();
    ?>

    Ejemplo #2 Estilo por procedimientos

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

    /* Verificación de la conexión */
    if (mysqli_connect_errno()) {
    printf("Fallo en la conexión: %s\n", mysqli_connect_error());
    exit();
    }

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

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

    /* Obtener información del campo para la columna 'SurfaceArea' */
    $finfo = mysqli_fetch_field_direct($result, 1);

    printf("Nombre : %s\n", $finfo->name);
    printf("Tabla : %s\n", $finfo->table);
    printf("Tamaño máx : %d\n", $finfo->max_length);
    printf("Flags : %d\n", $finfo->flags);
    printf("Tipo : %d\n", $finfo->type);

    mysqli_free_result($result);
    }

    /* Cierre de la conexión */
    mysqli_close($link);
    ?>

    El resultado de los ejemplos sería:

    Nombre      : SurfaceArea
Tabla       : Country
Tamaño máx : 10
Flags       : 32769
Tipo        : 4

    Ver también

    Found A Problem?

    Learn How To Improve This Page • Submit a Pull Request • Report a Bug
    ＋add a note

    User Contributed Notes 12 notes

    up
    16
    daniel at summit cove dot com
    16 years ago
    Here's a bigger list of data types. I got this by creating every type I could and calling fetch_fields():

    <?php
    $mysql_data_type_hash     = array(
    1=>'tinyint',
    2=>'smallint',
    3=>'int',
    4=>'float',
    5=>'double',
    7=>'timestamp',
    8=>'bigint',
    9=>'mediumint',
    10=>'date',
    11=>'time',
    12=>'datetime',
    13=>'year',
    16=>'bit',
    //252 is currently mapped to all text and blob types (MySQL 5.0.51a)
    253=>'varchar',
    254=>'char',
    246=>'decimal'
    );
    ?>
    up
    7
    ben dot NOSPAM at NOSPAM dot seraphire dot com
    12 years ago
    This may be obvious, but the constants for the field types are already defined in PHP, and can be found in the documentation at: http://php.net/manual/en/mysqli.constants.php
    up
    6
    cjs at ashdowntech dot com
    16 years ago
    According to
    http://www.redferni.uklinux.net/mysql/MySQL-Protocol.html

    Data type values are:

    DECIMAL 0 ENUM 247
    TINY 1 SET 248
    SHORT 2 TINY_BLOB 249
    LONG 3 MEDIUM_BLOB 250
    FLOAT 4 LONG_BLOB 251
    DOUBLE 5 BLOB 252
    NULL 6 VAR_STRING 253
    TIMESTAMP 7 STRING 254
    LONGLONG 8 GEOMETRY 255
    INT24 9
    DATE 10
    TIME 11
    DATETIME 12
    YEAR 13
    NEWDATE 14

    Note that this is not tested and does not contain
    all the values noted by deluxmozart
    up
    5
    cjs at ashdowntech dot com
    16 years ago
    According to
    dev.mysql.com/sources/doxygen/mysql-5.1/mysql__com_8h-source.html
    the flag bits are:

    NOT_NULL_FLAG 1 /* Field can't be NULL */
    PRI_KEY_FLAG 2 /* Field is part of a primary key */
    UNIQUE_KEY_FLAG 4 /* Field is part of a unique key */
    MULTIPLE_KEY_FLAG 8 /* Field is part of a key */
    BLOB_FLAG 16 /* Field is a blob */
    UNSIGNED_FLAG 32 /* Field is unsigned */
    ZEROFILL_FLAG 64 /* Field is zerofill */
    BINARY_FLAG 128 /* Field is binary */
    ENUM_FLAG 256 /* field is an enum */
    AUTO_INCREMENT_FLAG 512 /* field is a autoincrement field */
    TIMESTAMP_FLAG 1024 /* Field is a timestamp */
    up
    2
    andre at koethur dot de
    11 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
    gmx dot net at Hoffmann dot P
    11 years ago
    Warning!
    This function is not only more memory consuming than expected but the consumption also depends on the size of the result set. So if you realy only want to get your field_names you might want to append " LIMIT 1" or use mysqli->unbuffered_query() to save yourself from a memory bloat.
    up
    1
    shoresofnowhere at gmail dot com
    15 years ago
    Beware of the fact that the ->def property NEVER gets filled with the correct default field value, so it's totally USELESS.

    This happens NOT for a bug in php (so don't go filling in a bug report), but happens BY DESIGN, since the MySQL C API call doesn't fill in this value, unless you call the mysql_list_fields() function, which Php doesn't.

    See here for reference.
    http://dev.mysql.com/doc/refman/5.0/en/c-api-datatypes.html

    Also, be aware that if you're using a query which contains subqueries, the primary key/autoincrement flags do NOT get passed along, even if the field you're looking at is the primary autoincrement key of the master table:

    SELECT * from (SELECT id from areas) AS subareas

    and you'll find primary key and autoinc flags off on id field, even if id was the primary autoinc key of areas table.

    This also is by design, i think, since it's supposed that if we're using a subquery then the primary key/autoinc stuff might have no sense at all, since in the result set we can compose fileds from many different tables.

    Hoping this is useful, bye!
    up
    0
    anatoliy at ukhvanovy dot name
    10 years ago
    You can find all available data types here:
    https://php.net/manual/ru/mysqli.constants.php
    (search "MYSQLI_TYPE_" in your browser)
    up
    -1
    Anonymous
    4 years ago
    JSON type is 245 if anyone is wondering.
    up
    -1
    bl at example dot com
    14 years ago
    note that
    "SELECT <timestamp-field>, ..."
    will return the field with type 7 (timestamp) but with content like "2010-07-14 14:35:08". the point being it is a string.

    "SELECT <timestamp-field> + 0, ..."
    returns a type 5 (double) but while a number, is not seconds since epoch, but a number in MySQL's "YYYYMMDDHHMMSS" format, in this example:
    20100714143508

    (PHP 5.2.12)
    up
    -1
    deluxmozart at yahoo dot de
    16 years ago
    Here are some Numbers of Datatypes. I searched for it but i didn't find a list, where the datatypes of the numbers are listed.

    so first I can give this:

    3 - Int
    10 - Date
    246 - Decimal
    252 - text
    253 - VarChar
    254 - Boolean
    up
    -3
    gcdreak at example dot com
    15 years ago
    I wrote a simple class to get info about fields.
    Try it!

    <?php
    class MysqlFieldsInfo implements Iterator
    {

    private     $result;
    private     $position;
    private     $row;


    function     __construct($result){
    $this->result = $result;
    $this->position = 0;
    $this->rewind(); // W $results wewnętrzny wskaźnik może być przesunięty więc powracamy do początku
    }

    public function     current(){
    return     $this->row;
    }

    public function     next(){
    $this->position++;
    $this->row = $this->result->fetch_field();
    }

    public function     valid(){
    return (boolean)     $this->row;
    }

    public function     key(){
    return     $this->position;
    }

    public function     rewind(){
    $this->position = 0;
    $this->result->field_seek(0);
    $this->next();
    }

    // This function show data in table
    public function export(){

    echo     '<table id="db_table_info">';
    echo     '<tr>
    <th>Name</th>
    <th>Orgname</th>
    <th>Table</th>
    <th>Orgtable</th>
    <th>Def</th>
    <th>Max_length</th>
    <th>Length</th>
    <th>Charsetnr</th>
    <th>Flags</th>
    <th>Type</th>
    <th>Decimals</th>
    </tr>'    ;
    while(    $this->valid()){
    echo     '<tr>';
    printf("\n\t<td>%s</td>\n", $this->current()->name);
    printf("\t<td>%s</td>\n", $this->current()->orgname);
    printf("\t<td>%s</td>\n", $this->current()->orgtable);
    printf("\t<td>%s</td>\n", $this->current()->def);
    printf("\t<td>%s</td>\n", $this->current()->max_length);
    printf("\t<td>%s</td>\n", $this->current()->length);
    printf("\t<td>%s</td>\n", $this->current()->charsetnr);
    printf("\t<td>%s</td>\n", $this->current()->flags);
    printf("\t<td>%s</td>\n", $this->current()->type);
    printf("\t<td>%s</td>\n", $this->current()->decimals);

    echo     '</tr>';

    $this->next();
    }

    echo     '</table>';
    }
    }
    ?>
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