(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Fetch meta-data for a single field
Object-oriented style
Procedural style
Returns an object which contains field definition information from the specified result set.
resultProcedural style only: A mysqli_result object returned by mysqli_query(), mysqli_store_result(), mysqli_use_result() or mysqli_stmt_get_result().
index
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 index is
available.
| Property | 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 | Unused. Always an empty string |
| db | The name of the database |
| catalog | Unused. Always "def" |
| max_length | The maximum width of the field for the result set. As of PHP 8.1, this value is always 0. |
| length |
The width of the field in bytes. For string columns,
the length value varies on the connection character set. For example,
if the character set is latin1, a single-byte character set,
the length value for a SELECT 'abc' query is 3.
If the character set is utf8mb4, a multibyte character
set in which characters take up to 4 bytes, the length value is 12.
|
| 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 for numeric fields, and the fractional seconds precision for temporal fields. |
Example #1 Object-oriented style
<?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();
?>Example #2 Procedural style
<?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);
?>The above examples will output:
Name: SurfaceArea Table: Country max. Len: 10 Flags: 32769 Type: 4
Here's a bigger list of data types. I got this by creating every type I could and calling fetch_fields():
<?php
$mysql_data_type_hash = array(
1=>'tinyint',
2=>'smallint',
3=>'int',
4=>'float',
5=>'double',
7=>'timestamp',
8=>'bigint',
9=>'mediumint',
10=>'date',
11=>'time',
12=>'datetime',
13=>'year',
16=>'bit',
//252 is currently mapped to all text and blob types (MySQL 5.0.51a)
253=>'varchar',
254=>'char',
246=>'decimal'
);
?>This may be obvious, but the constants for the field types are already defined in PHP, and can be found in the documentation at: http://php.net/manual/en/mysqli.constants.phpAccording to
http://www.redferni.uklinux.net/mysql/MySQL-Protocol.html
Data type values are:
DECIMAL 0 ENUM 247
TINY 1 SET 248
SHORT 2 TINY_BLOB 249
LONG 3 MEDIUM_BLOB 250
FLOAT 4 LONG_BLOB 251
DOUBLE 5 BLOB 252
NULL 6 VAR_STRING 253
TIMESTAMP 7 STRING 254
LONGLONG 8 GEOMETRY 255
INT24 9
DATE 10
TIME 11
DATETIME 12
YEAR 13
NEWDATE 14
Note that this is not tested and does not contain
all the values noted by deluxmozartAccording to
dev.mysql.com/sources/doxygen/mysql-5.1/mysql__com_8h-source.html
the flag bits are:
NOT_NULL_FLAG 1 /* Field can't be NULL */
PRI_KEY_FLAG 2 /* Field is part of a primary key */
UNIQUE_KEY_FLAG 4 /* Field is part of a unique key */
MULTIPLE_KEY_FLAG 8 /* Field is part of a key */
BLOB_FLAG 16 /* Field is a blob */
UNSIGNED_FLAG 32 /* Field is unsigned */
ZEROFILL_FLAG 64 /* Field is zerofill */
BINARY_FLAG 128 /* Field is binary */
ENUM_FLAG 256 /* field is an enum */
AUTO_INCREMENT_FLAG 512 /* field is a autoincrement field */
TIMESTAMP_FLAG 1024 /* Field is a timestamp */Here are two methods for converting the 'type' and 'flags' attributes to text for debugging purposes. They both use the predefined MYSQLI_ constants to generate the text.
<?php
public static function h_type2txt($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);
}
?>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.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!You can find all available data types here:
https://php.net/manual/ru/mysqli.constants.php
(search "MYSQLI_TYPE_" in your browser)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>';
}
}
?>