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 index 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.

    示例

    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);
    ?>

    以上示例会输出：

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

    参见

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    ＋添加备注

    用户贡献的备注 12 notes

    up
    15
    daniel at summit cove dot com
    15 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'
    );
    ?>
    up
    3
    cjs at ashdowntech dot com
    16 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 */
    up
    4
    ben dot NOSPAM at NOSPAM dot seraphire dot com
    11 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
    up
    4
    cjs at ashdowntech dot com
    16 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
    up
    2
    andre at koethur dot de
    10 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);
    }

    ?>
    up
    0
    anatoliy at ukhvanovy dot name
    9 years ago
    You can find all available data types here:
    https://php.net/manual/ru/mysqli.constants.php
    (search "MYSQLI_TYPE_" in your browser)
    up
    0
    gmx dot net at Hoffmann dot P
    10 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.
    up
    -1
    Anonymous
    4 years ago
    JSON type is 245 if anyone is wondering.
    up
    0
    shoresofnowhere at gmail dot com
    15 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!
    up
    -1
    bl at example dot com
    14 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)
    up
    -1
    deluxmozart at yahoo dot de
    16 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
    up
    -2
    gcdreak at example dot com
    15 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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