PHP - Manual: mysqli_result::fetch_field_direct

2024-12-21

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mysqli_result::fetch_field_direct

mysqli_fetch_field_direct

(PHP 5, PHP 7, PHP 8)

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

说明

面向对象风格

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

过程化风格

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

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()、 mysqli_use_result()、mysqli_stmt_get_result() 返回的 mysqli_result 对象。
index: 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

示例 #1 面向对象风格


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

/* check connection */
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)) {

    /* Get field information for column 'SurfaceArea' */
    $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();
}

/* close connection */
$mysqli->close();
?>

示例 #2 过程化风格


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

/* check connection */
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)) {

    /* Get field information for column 'SurfaceArea' */
    $finfo = mysqli_fetch_field_direct($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);
}

/* close connection */
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() - Gets the number of fields in the result set
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

add a note

User Contributed Notes 12 notes

down

daniel at summit cove dot com ¶

13 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'
);
?>

down

cjs at ashdowntech dot com ¶

13 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 */

down

ben dot NOSPAM at NOSPAM dot seraphire dot com ¶

9 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

down

cjs at ashdowntech dot com ¶

13 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

down

andre at koethur dot de ¶

8 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);
}

?>

down

anatoliy at ukhvanovy dot name ¶

7 years ago


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

down

gmx dot net at Hoffmann dot P ¶

8 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.

down

-1

Anonymous ¶

1 year ago


JSON type is 245 if anyone is wondering.

down

shoresofnowhere at gmail dot com ¶

12 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!

down

-1

bl at example dot com ¶

11 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)

down

-1

deluxmozart at yahoo dot de ¶

13 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

down

-2

gcdreak at example dot com ¶

12 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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官方地址：https://www.php.net/manual/en/mysqli-result.fetch-field-direct.php

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mysqli_result::fetch_field_direct

mysqli_fetch_field_direct

说明

参数

返回值

范例

参见

User Contributed Notes 12 notes