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이 문서에서는 PHP 중국어 웹사이트 매뉴얼 풀어 주다
(PHP 5)
mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Fetch meta-data for a single field
面向对象风格
$fieldnr
)过程化风格
$result
, int $fieldnr
)Returns an object which contains field definition information from the specified result set.
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.
Returns an object which contains field definition information or FALSE
if no field information for specified fieldnr is
available.
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) |
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 ( $link );
?>
以上例程会输出:
Name: SurfaceArea Table: Country max. Len: 10 Flags: 32769 Type: 4
[#1] anatoliy at ukhvanovy dot name [2015-03-21 22:58:18]
You can find all available data types here:
https://php.net/manual/ru/mysqli.constants.php
(search "MYSQLI_TYPE_" in your browser)
[#2] gmx dot net at Hoffmann dot P [2014-06-18 13:32:14]
Warning!
This function is not only more memory consuming than expected but the consumption also depends on the size of the result set. So if you realy only want to get your field_names you might want to append " LIMIT 1" or use mysqli->unbuffered_query() to save yourself from a memory bloat.
[#3] andre at koethur dot de [2014-04-20 07:53:57]
Here are two methods for converting the 'type' and 'flags' attributes to text for debugging purposes. They both use the predefined MYSQLI_ constants to generate the text.
<?php
public static function h_type2txt($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