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');?>

According todev.mysql.com/sources/doxygen/mysql-5.1/mysql__com_8h-source.htmlthe 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 */

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

According tohttp://www.redferni.uklinux.net/mysql/MySQL-Protocol.htmlData type values are:DECIMAL           0       ENUM           247TINY              1       SET            248SHORT             2       TINY_BLOB      249LONG              3       MEDIUM_BLOB    250FLOAT             4       LONG_BLOB      251DOUBLE            5       BLOB           252NULL              6       VAR_STRING     253TIMESTAMP         7       STRING         254LONGLONG          8       GEOMETRY       255INT24             9DATE             10TIME             11DATETIME         12YEAR             13NEWDATE          14Note that this is not tested and does not containall the values noted by deluxmozart

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);}?>

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

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.

JSON type is 245 if anyone is wondering.

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.htmlAlso, 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 subareasand 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!

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    -    Boolean

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>';                }            }?>