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mysqli_result::fetch_field_direct

mysqli_fetch_field_direct

(PHP 5)

mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Fetch meta-data for a single field

说明

面向对象风格

object mysqli_result::fetch_field_direct ( int $fieldnr )

过程化风格

object mysqli_fetch_field_direct ( mysqli_result $result , int $fieldnr )

Returns an object which contains field definition information from the specified result set.

参数

result

仅以过程化样式：由 mysqli_query() ， mysqli_store_result() 或 mysqli_use_result() 返回的结果集标识。

fieldnr

The field number. This value must be in the range from 0 to number of fields - 1.

返回值

Returns an object which contains field definition information or FALSE if no field information for specified fieldnr is available.

Object attributes
Attribute Description
name The name of the column
orgname Original column name if an alias was specified
table The name of the table this field belongs to (if not calculated)
orgtable Original table name if an alias was specified
def The default value for this field, represented as a string
max_length The maximum width of the field for the result set.
length The width of the field, as specified in the table definition.
charsetnr The character set number for the field.
flags An integer representing the bit-flags for the field.
type The data type used for this field
decimals The number of decimals used (for numeric fields)

范例

Example #1 面向对象风格

<?php
$mysqli  = new  mysqli ( "localhost" ,  "my_user" ,  "my_password" ,  "world" );
if ( mysqli_connect_errno ()) {
     printf ( "Connect failed: %s\n" ,  mysqli_connect_error ());
    exit();
}

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

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

    
     $finfo  =  $result -> fetch_field_direct ( 1 );

     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" ,  $finfo -> type );

     $result -> close ();
}
$mysqli -> close ();
 ?>

Example #2 过程化风格

<?php
$link  =  mysqli_connect ( "localhost" ,  "my_user" ,  "my_password" ,  "world" );
if ( mysqli_connect_errno ()) {
     printf ( "Connect failed: %s\n" ,  mysqli_connect_error ());
    exit();
}

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

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

    
     $finfo  =  mysqli_fetch_field_direct ( $result ,  1 );

     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" ,  $finfo -> type );

     mysqli_free_result ( $result );
}
mysqli_close ( $link );
 ?>

以上例程会输出：

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

参见

  • mysqli_num_fields() - Get the number of fields in a result
  • mysqli_fetch_field() - Returns the next field in the result set
  • mysqli_fetch_fields() - Returns an array of objects representing the fields in a result set

用户评论:

[#1] anatoliy at ukhvanovy dot name [2015-03-21 22:58:18]

You can find all available data types here:
https://php.net/manual/ru/mysqli.constants.php
(search "MYSQLI_TYPE_" in your browser)

[#2] gmx dot net at Hoffmann dot P [2014-06-18 13:32:14]

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.

[#3] andre at koethur dot de [2014-04-20 07:53:57]

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);
}

?>

[#4] ben dot NOSPAM at NOSPAM dot seraphire dot com [2012-12-06 16:01:36]

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

[#5] bl at example dot com [2010-08-09 22:11:26]

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)

[#6] shoresofnowhere at gmail dot com [2009-08-26 03:50:31]

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!

[#7] gcdreak at example dot com [2009-08-18 15:28:15]

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 wewn?trzny wska?nik mo?e by? przesuni?ty wi?c powracamy do pocz?tku
                }
                
                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>';
                }
            }
?>

[#8] daniel at summit cove dot com [2009-02-22 15:36:43]

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'
);
?>

[#9] cjs at ashdowntech dot com [2008-09-16 21:52:27]

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

[#10] cjs at ashdowntech dot com [2008-09-12 20:00:20]

According to
dev.mysql.com/sources/doxygen/mysql-5.1/mysql__com_8h-source.html
the flag bits are:
 
 NOT_NULL_FLAG          1         
 PRI_KEY_FLAG           2         
 UNIQUE_KEY_FLAG        4         
 MULTIPLE_KEY_FLAG      8         
 BLOB_FLAG             16         
 UNSIGNED_FLAG         32         
 ZEROFILL_FLAG         64         
 BINARY_FLAG          128         
 ENUM_FLAG            256         
 AUTO_INCREMENT_FLAG  512         
 TIMESTAMP_FLAG      1024         

[#11] deluxmozart at yahoo dot de [2008-07-24 11:05:23]

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

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