mysqli_result::fetch_field

mysqli_fetch_field

(PHP 5, PHP 7, PHP 8)

mysqli_result::fetch_field -- mysqli_fetch_fieldReturns the next field in the result set

Опис

Об'єктно-орієнтований стиль

public mysqli_result::fetch_field(): object|false

Процедурний стиль

mysqli_fetch_field(mysqli_result $result): object|false

Returns the definition of one column of a result set as an object. Call this function repeatedly to retrieve information about all columns in the result set.

Параметри

result

Тільки процедурний стиль: об'єкт mysqli_result, якого повертає одна з функцій mysqli_query(), mysqli_store_result(), mysqli_use_result() або mysqli_stmt_get_result().

Значення, що повертаються

Returns an object which contains field definition information or false if no field information is available.

Object properties
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.

Приклади

Приклад #1 Об'єктно-орієнтований стиль

<?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 Code LIMIT 5";

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

/* Get field information for all columns */
while ($finfo = $result->fetch_field()) {

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\n", $finfo->type);
}
$result->close();
}

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

Приклад #2 Процедурний стиль

<?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 Code LIMIT 5";

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

/* Get field information for all fields */
while ($finfo = mysqli_fetch_field($result)) {

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\n", $finfo->type);
}
mysqli_free_result($result);
}

/* close connection */
mysqli_close($link);
?>

Подані вище приклади виведуть:

Name:     Name
Table:    Country
max. Len: 11
Flags:    1
Type:     254

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

Прогляньте також

add a note

User Contributed Notes 8 notes

up
52
iansoko at hotmail dot com
13 years ago
here are the data types that correspond to the TYPE number returned by fetch_field. thought i would post this here since i couldn't find the info elsewhere.numerics -------------BIT: 16TINYINT: 1BOOL: 1SMALLINT: 2MEDIUMINT: 9INTEGER: 3BIGINT: 8SERIAL: 8FLOAT: 4DOUBLE: 5DECIMAL: 246NUMERIC: 246FIXED: 246dates------------DATE: 10DATETIME: 12TIMESTAMP: 7TIME: 11YEAR: 13strings & binary------------CHAR: 254VARCHAR: 253ENUM: 254SET: 254BINARY: 254VARBINARY: 253TINYBLOB: 252BLOB: 252MEDIUMBLOB: 252TINYTEXT: 252TEXT: 252MEDIUMTEXT: 252LONGTEXT: 252
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15
ragtag at hotmail dot com
16 years ago
The flags used by MySql are:                                                                                                                                                   NOT_NULL_FLAG = 1                                                                                     PRI_KEY_FLAG = 2                                                                                      UNIQUE_KEY_FLAG = 4                                                                                   BLOB_FLAG = 16                                                                                        UNSIGNED_FLAG = 32                                                                                    ZEROFILL_FLAG = 64                                                                                    BINARY_FLAG = 128                                                                                     ENUM_FLAG = 256                                                                                       AUTO_INCREMENT_FLAG = 512                                                                             TIMESTAMP_FLAG = 1024                                                                                 SET_FLAG = 2048                                                                                       NUM_FLAG = 32768                                                                                      PART_KEY_FLAG = 16384                                                                                 GROUP_FLAG = 32768                                                                                    UNIQUE_FLAG = 65536                                                                            To test if a flag is set you can use & like so:<?php$meta = $mysqli_result_object->fetch_field();if ($meta->flags & 4) {   echo 'Unique key flag is set'; } ?>
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3
andre at koethur dot de
11 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.<?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(' ', $result);}?>
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1
sofe2038 at gmail dot com
7 years ago
The constants in a few other comments above appear to be inaccurate. Here are some more official references that seem quite hard to search.The "type" attribute: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-typeThe "flags" attribute: https://github.com/google/mysql/blob/master/include/mysql_com.h#L133In addition, all attributes are explained on the COM_QUERY_RESPONSE page too: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition
up
1
rvila at revolutionvisualarts dot com
8 years ago
The predefined constant values returned by the function get_predefined_constants() for:MYSQLI_TYPE_CHAR = 1MYSQLI _TYPE_TINYINT = 1If the code is used to categorized the type of field use this values will of course create confusion. For example:if($fieldtype === "CHAR"){    $field_html_attribute = "text";    $field_html_length = 1;} elseif($fieldtype === "TINYINT") {    $field_html_attribute = "number";    $field_html_length = 1;}If an array is created to set the key as the numeric value and the value of that key as the the text title, TINYINT will be replaced by CHAR value. But is this process is reversed, then the code will select TINYINT if the foreach statement set to break when the numeric value of the flag equals the value of the current key as the first intance.Base in the note added by Johnathan at http://php.net/manual/en/mysqli.field-count.php the values should be:CHAR = 254TINYINT = 1But predefined function attributes the value 254 to MYSQLI_TYPE_STRING.Just for FYI
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2
miqrogroove at gmail dot com
12 years ago
Beware the values of the predefined constants.  They do not always correlate with the actual field types.  For example:MYSQLI_TYPE_BLOB: 252MYSQLI_TYPE_TINY_BLOB: 249MYSQLI_TYPE_MEDIUM_BLOB: 250MYSQLI_TYPE_LONG_BLOB: 251MySQLi will indeed return a value of 252 for a tinytext field, but as you can see, this does not correspond to the value of MYSQLI_TYPE_TINY_BLOB.
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0
nick
7 years ago
It is not possible to get the values for an enum or set field through fetch_fields(). As far as I can tell this is because it hasn't been implemented in the mysqlnd api but whatever the reason it is not possible and you must issue a query like SHOW COLUMNS directly and interrogate the result to determine them.Incidentally you need to check the enum_flag rather than look for the enum_type to determine whether a field is enum or not. The type returned is usually some kind of string.
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2
Anonymous
13 years ago
The constants for the TYPE number returned by fetch_field are enumerated here (MYSQLI_TYPE_*):http://php.net/manual/en/mysqli.constants.php
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