(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Obtener los metadatos de un único campo
Estilo orientado a objetos
Estilo por procedimientos
Devuelve un objeto que contiene la información de definición de un campo del conjunto de resultados especificado.
resultSólo estilo por procedimientos: Un conjunto de identificadores de resultados devuelto por mysqli_query(), mysqli_store_result() o mysqli_use_result().
fieldnr
El número de campo. Este valor debe estar en un rango desde
0 a número de campos - 1.
Devuelve un objeto que contiene la información de definición del campo o false
si no está disponible la información del campo especificada por
fieldnr.
| Atributo | Descripción |
|---|---|
| name | El nombre de la columna |
| orgname | El nombre original de la columna si se especificó un alias |
| table | El nombre de la tabla al que pertenece el campo (si no es calculado) |
| orgtable | El nombre original de la tabla si se especificó un alias |
| def | El valor predeterminado de este campo, representado como una cadena |
| max_length | El ancho máximo del campo del conjunto de resultados. |
| length | El ancho del campo, como fue especificado en la definición de la tabla. |
| charsetnr | El número del conjunto de caracteres del campo. |
| flags | Un entero que representa las banderas de bits del campo. |
| type | El tipo de datos usado por el campo |
| decimals | El número de decimales empleados (para campos numéricos) |
Ejemplo #1 Estilo orientado a objetos
<?php
$mysqli = new mysqli("localhost", "mi_usuario", "mi_contraseña", "world");
/* comprobar la conexión */
if (mysqli_connect_errno()) {
printf("Falló la conexión: %s\n", mysqli_connect_error());
exit();
}
$consulta = "SELECT Name, SurfaceArea from Country ORDER BY Name LIMIT 5";
if ($resultado = $mysqli->query($consulta)) {
/* Obtener la información del campo para la columna 'SurfaceArea' */
$info_campo = $resultado->fetch_field_direct(1);
printf("Nombre: %s\n", $info_campo->name);
printf("Tabla: %s\n", $info_campo->table);
printf("Longitud máx.: %d\n", $info_campo->max_length);
printf("Banderas: %d\n", $info_campo->flags);
printf("Tipo: %d\n", $info_campo->type);
$resultado->close();
}
/* cerrar la conexión */
$mysqli->close();
?>Ejemplo #2 Estilo por procedimientos
<?php
$enlace = mysqli_connect("localhost", "mi_usuario", "mi_contraseña", "world");
/* comprobar la conexión */
if (mysqli_connect_errno()) {
printf("Falló la conexión: %s\n", mysqli_connect_error());
exit();
}
$consulta = "SELECT Name, SurfaceArea from Country ORDER BY Name LIMIT 5";
if ($resultado = mysqli_query($enlace, $consulta)) {
/* Obtener la información del campo para la columna 'SurfaceArea' */
$info_campo = mysqli_fetch_field_direct($resultado, 1);
printf("Nombre: %s\n", $info_campo->name);
printf("Tabla: %s\n", $info_campo->table);
printf("Longitud máx.: %d\n", $info_campo->max_length);
printf("Banderas: %d\n", $info_campo->flags);
printf("Tipo: %d\n", $info_campo->type);
mysqli_free_result($resultado);
}
/* cerrar la conexión */
mysqli_close($enlace);
?>El resultado de los ejemplos sería:
Nombre: SurfaceArea Tabla: Country Longitud máx.: 10 Banderas: 32769 Tipo: 4
Here's a bigger list of data types. I got this by creating every type I could and calling fetch_fields():<?php$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');?>According todev.mysql.com/sources/doxygen/mysql-5.1/mysql__com_8h-source.htmlthe 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 */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.phpAccording tohttp://www.redferni.uklinux.net/mysql/MySQL-Protocol.htmlData type values are:DECIMAL 0 ENUM 247TINY 1 SET 248SHORT 2 TINY_BLOB 249LONG 3 MEDIUM_BLOB 250FLOAT 4 LONG_BLOB 251DOUBLE 5 BLOB 252NULL 6 VAR_STRING 253TIMESTAMP 7 STRING 254LONGLONG 8 GEOMETRY 255INT24 9DATE 10TIME 11DATETIME 12YEAR 13NEWDATE 14Note that this is not tested and does not containall the values noted by deluxmozartHere 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.<?phppublic 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);}?>You can find all available data types here:https://php.net/manual/ru/mysqli.constants.php(search "MYSQLI_TYPE_" in your browser)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.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.htmlAlso, 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 subareasand 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!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)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 - BooleanI 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>'; } }?>