That huge difference in timings may be caused by database cache issues. If mysql_fetch_object() was the first function to be used, the cache was empty, but subsequent invocations took the result from the query cache.
(PHP 4, PHP 5)
mysql_fetch_object — 从结果集中取得一行作为对象
$result
)
返回根据所取得的行生成的对象，如果没有更多行则返回 FALSE。
mysql_fetch_object() 和 mysql_fetch_array() 类似，只有一点区别 - 返回一个对象而不是数组。间接地也意味着只能通过字段名来访问数组，而不是偏移量（数字是合法的属性名）。
Note: 此函数返回的字段名大小写敏感。
<?php
/* this is valid */
echo $row->field;
/* this is invalid */
echo $row->0;
?>
速度上，本函数和 mysql_fetch_array() 一样，也几乎和 mysql_fetch_row() 一样快（差别很不明显）。
Example #1 mysql_fetch_object() 例子
<?php
mysql_connect("hostname", "user", "password");
mysql_select_db("mydb");
$result = mysql_query("select * from mytable");
while ($row = mysql_fetch_object($result)) {
echo $row->user_id;
echo $row->fullname;
}
mysql_free_result($result);
?>
参见 mysql_fetch_array()，mysql_fetch_assoc() 和 mysql_fetch_row()。
resultresource 型的结果集。此结果集来自对 mysql_query() 的调用。
class_nameThe name of the class to instantiate, set the properties of and return. If not specified, a stdClass object is returned.
params
An optional array of parameters to pass to the constructor
for class_name objects.
Returns an object with string properties that correspond to the
fetched row, or FALSE if there are no more rows.
| 版本 | 说明 |
|---|---|
| 5.0.0 | Added the ability to return as a different object. |
Example #2 mysql_fetch_object() example
<?php
mysql_connect("hostname", "user", "password");
mysql_select_db("mydb");
$result = mysql_query("select * from mytable");
while ($row = mysql_fetch_object($result)) {
echo $row->user_id;
echo $row->fullname;
}
mysql_free_result($result);
?>
Example #3 mysql_fetch_object() example
<?php
class foo {
public $name;
}
mysql_connect("hostname", "user", "password");
mysql_select_db("mydb");
$result = mysql_query("select name from mytable limit 1");
$obj = mysql_fetch_object($result, 'foo');
var_dump($obj);
?>
Note: Performance
Speed-wise, the function is identical to mysql_fetch_array(), and almost as quick as mysql_fetch_row() (the difference is insignificant).
Note:
mysql_fetch_object() is similar to mysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names).
Note: 此函数返回的字段名大小写敏感。
Note: 此函数将 NULL 字段设置为 PHP
NULL值。
That huge difference in timings may be caused by database cache issues. If mysql_fetch_object() was the first function to be used, the cache was empty, but subsequent invocations took the result from the query cache.
When working with a stdClass object returned from a database query, specifically:
$object = mysql_fetch_object($result)
You may run into assignment problems if you have a field with a '.' in the name.
e.g.: `user.id`
To remedy this situation, you can use curly braces and single quotes during assignment.
In place of:
$myObject->user_id = $object->user.id;
Use:
$myObject->user_id = $object->{'user.id'};
I created a table, with 5 INT columns, and 1000 rows of random ints.
I did 100 selects:
SELECT * FROM bench... (mysql_fetch_object)
Query time: 5.40725040436
Fetching time: 16.2730708122 (avg: 1.32130565643E-5)
Total time: 21.6803212166
SELECT * FROM bench... (mysql_fetch_array)
Query time: 5.37693023682
Fetching time: 10.3851644993 (avg: 7.48886537552E-6)
Total time: 15.7620947361
SELECT * FROM bench... (mysql_fetch_assoc)
Query time: 5.345921278
Fetching time: 10.6170959473 (avg: 7.64049530029E-6)
Total time: 15.9630172253
"Note: Performance Speed-wise, the function is identical to mysql_fetch_array(), and almost as quick as mysql_fetch_row() (the difference is insignificant)."
And I am a penguin :)
<?php
class Test {
public $go ;
private $id ;
function show() {
return "id: {$this->id} go: {$this->go}" ;
}
function __construct()
{
echo "in __construct() ". $this->show() ."\n" ;
$this->go = uniqid() ;
}
}
if (! ($res = mysql_query('SELECT * FROM `test`', $db))) {
die('Invalid query: ' . mysql_error() . "\n");
}
while($obj = mysql_fetch_object($res, 'Test') ){
echo "outside ________ ". $obj->show() ."\n\n";
}
?>
This code gives the result:
in __construct() id: 1 go: first
outside ________ id: 1 go: 4845bd99ca2e3
in __construct() id: 2 go: second
outside ________ id: 2 go: 4845bd99ca2fd
It means that __construct() is invoked after filling fields with data from database, eg. it can be used to change strings into integers.
This is another way to load variables quickly within $this, and allows for intervention on variable names.
All columns from the single-row result are loaded and accessed via $this->_variableName.
<?
class MyClass{
public function _load($nID) {
$Q = "SELECT * FROM myTable";
if($aTmp = RETURN_Q_ARRAY($Q)) {
$aTmp = $aTmp[0];
$aK =array_keys($aTmp);
foreach($aK as $sK) {
if(!is_numeric($sK)) $this->{"_$sK"}=$aTmp[$sK];
}
return true;
}
return false;
}
}
$o = new MyClass;
$o->_load(1);
echo $o->_id; //1
echo $o->_otherColumn; //otherColumn value
If you're using mysql_fetch_object and specifying a class - the properties will be set BEFORE the constructor is executed. This is generally not an issue, but can cause some major problems if you're properties are set via the __set() magic method and constructor logic must be executed first.
@Jezze : This wil also work. Also works with static methods.
<?php
class Foo
{
private $FooBar;
public function LoadFromId($Id)
{
$Result = mysql_query('SELECT * FROM foo WHERE Id = ' . $Id);
while($Row = mysql_fetch_object($Result, __CLASS__))
{
print_r($Row);
}
}
}
$Foo = new Foo;
$Foo->LoadAll();
?>
If you have a class that represents itself in a database you can use this function to get the properties.
class MyClass {
public $name;
public $language;
function load($id) {
$query = mysql_query("SELECT name, language FROM myTable WHERE id = $id");
$result = mysql_fetch_object($query, get_class($this));
foreach(get_object_vars($result) as $var => $value) $this->$var = $value;
}
}
$a = new MyClass();
$a->load(1);
In reply to rodolphe dot bodeau at free dot fr :
The function mysql_fetch_object has other two parameters that you can use.
As the manual say:
mysql_fetch_object( $resource, $class_name, $params ) )
$class_name and $params are optional.
So if you want to fetch a row in a class you can:
1) Define your class Test with method and other stuff.
2) Execute Query
3) call:
$Object = mysql_fetch_object( $Resource, "Test" );
so you can use $Object with the methods
Be aware how you write code in your methods: in this case, classes are used for centralize the code and they are not
really safe because you can have an additional Information
( with a Join Query for example ) without methods to access to them.
So classes need get and set method generalized.
( for extra see PHP 5 Manual O'Rielly on the use of generalized methods get and set )
This little function stores the content of a mysql_fetch_object result into an object by using MySQL request field names as object parameters :
<?php
function FetchRequestInObject(&$obj, $req)
{
$ReqVars = get_object_vars($req);
foreach ($ReqVars as $ReqName => $ReqValue)
{
if (property_exists($obj, $ReqName))
{
$obj->$ReqName = $ReqValue;
}
}
}
?>
Remember that mysql_fetch_object is case sensitive, so beware of your object properties. Use keyword "AS" in your SQL request to change field name if necessary.
Since PHP 5.2.1 it seems like this function doesn't like queries that return columns with empty names, like:
select '' from `table`
PHP exits and mysql_error() does not return an error.
@Simon Paridon and others concerning SQL to php getting results via mysql_fetch_object:
Every query that would fail in a database frontend, such as MySQLs "Query Browser" and only will work by using the `-marks will probably give results hardly accessible in PHP especially if you have column names with "-" or " " in it.
Using the example of Simon Paridon: it is not possible to execute a query like:
SELECT id, user-id FROM unlucky_naming
only
SELECT id, `user-id` FROM unlucky_naming
will work...
so either be a bit wiser when naming the colums (e.g. user_id)
or try it with
SELECT id, `user-id` AS user_id FROM unlucky_naming
(i have not tested it in PHP yet, but i guess this will fail as well, if you have a query like "SELECT `foo name` FROM `unlucky naming 2`")
Somewhat down "amackenz at cs dot uml dot edu" mentioned to name sum, count etc. this may be a good hint for newbies: increase the speed of your php applications by using (my)sql native functions and save data transfer as well as processing time
The behavior of this function is slightly questionable.
If you have a col in you table containing non-variable-name characters like "-", mysql_fetch_object will add "impossible variable names" to your object, e.g.
object (
[user-id] => 7
)
You can not access this variable normally with $obj->user-id, because the variable name is invalid. But you can however access it like this:
$foo = 'user-id';
echo $obj->$foo;
It will correctly output 7, whereas var_dump($obj->user-id) would output int(0) for some reason.
I got this behaviour with PHP 4.4.2.
This is a very very elegant (and costless) way to fetch an enterie query to every single field name from a "wide" table:
The tedious way fetching:
<?php
$idtable=mysql_connect("localhost","user","pwd");
mysql_select_db("table",$idtable);
$consult=mysql_query("SELECT *
FROM models
ORDER BY Serie,Year ASC");
while($row=mysql_fetch_object($consult)){
$IdLomo=$row->IdLomo;
$Serie=$row->Serie;
$Model=$row->Model;
$Type=$row->Type;
$Year=$row->Year;
$Speed=$row->Speed;
$Power=$row->Power;
$Price=$row->Price;
$Load1=$row->Load1;
$Load2=$row->Load2;
$Load3=$row->Load3;
$Load4=$row->Load4;
$Server=$row->Servier;
$Real=$row->Real;
$Lomo=$row->Lomo;
}
?>
Resulting on 15 new variables called like their name on table wich we introduced manualy for 5 minutes. But imagine each row has 100 fields!
A way saving time with the same result:
<?php
$idtable=mysql_connect("localhost","user","pwd");
mysql_select_db("table",$idtable);
$consult=mysql_query("SELECT *
FROM models
ORDER BY Serie,Year ASC");
// We find the fields number
$numfields=mysql_num_fields($consult);
// Now we put the names of fields in a Array
for($i=0;$i<$numfields;$i++){
$fieldname[$i]=mysql_field_name($consult, $i);
}
while($row=mysql_fetch_object($consult)){
//Finally we assign the new variables
for($i=0;$i<$numfields;$i++){
$$fieldname[$i]=$row->$fieldname[$i];
}
}
?>
This method offers a nice way to fetch objects from databases. As Federico at Pomi dot net mentioned it doesn't work native as the type of the object fetched isn't the right one, but with a small typecast it works flawlessly.
<?php
function ClassTypeCast(&$obj,$class_type){
if(class_exists($class_type)){
$obj = unserialize(preg_replace("/^O:[0-9]+:\\"[^\"]+\\":/i",
"O:".strlen($class_type).":\\"".$class_type."\\":", serialize($obj)));
}
}
class Foo
{
var $foo;
var $bar;
function get_from_db()
{
mysql_connect();
mysql_select_db();
$res = mysql_query("SELECT foo,bar from my_table");
$fetched_object = mysql_fetch_object($res);
ClassTypeCast($fetched_object,"Foo");
$this = $fetched_object;
}
}
?>
Watch out for mysql_fetch_object() to return all values as strings.
if you try to do
<?
$p = mysql_fetch_object($some_sql);
// and then try to do something like
$money = $p->dollars + $p->cents;
?>
You may experience "Unsupported operand types"
so always cast them both as (int) 's!!
Some clarifications about previous notes concerning duplicate field names in a result set.
Consider the following relations:
TABLE_A(id, name)
TABLE_B(id, name, id_A)
Where TABLE_B.id_A references TABLE_A.id.
Now, if we join these tables like this: "SELECT * FROM TABLE_A, TABLE_B WHERE TABLE_A.id = TABLE_B.id_A", the result set looks like this: (id, name, id, name, id_A).
The behaviour of mysql_fetch_object on a result like this isn't documented here, but it seems obvious that some data will be lost because of the duplicate field names.
This can be avoided, as Eskil Kvalnes stated, by aliasing the field names. However, it is not necessary to alias all fields on a large table, as the following syntax is legal in MySQL: "SELECT *, TABLE_A.name AS name_a, TABLE_B.name AS name_b FROM TABLE_A, TABLE_B ...". This will produce a result set formatted like this: (id, name, id, name, id_A, name_a, name_b), and your data is saved. Hooray!
-q
In reviewing Eskil Kvalnes's comments (04-Mar-2003 11:59
When using table joins in a query you obviously need to name all the fields to make it work right with mysql_fetch_object()) I was left asking and, as a newbie, the reason why I'm here. I have a 28 field table. Ran SELECT * with a LEFT JOIN, etc and it appears to have worked on my test server without issue.
On further reading, MYSQL.COM has the following:
* It is not allowed to use a column alias in a WHERE clause, because the column value may not yet be determined when the WHERE clause is executed. See section A.5.4 Problems with alias.
* The FROM table_references clause indicates the tables from which to retrieve rows. If you name more than one table, you are performing a join. For information on join syntax, see section 6.4.1.1 JOIN Syntax. For each table specified, you may optionally specify an alias.
Aware of the fact there's a difference between tables and fields there appears to be confusion here somewhere.
Here is a wrapper that will allow specifying a class name.
function &db_fetch_object($set,$className)
{
/* Start by getting the usual array */
$row = mysql_fetch_assoc($set);
if ($row === null) return null;
/* Create the object */
$obj =& new $className();
/* Explode the array and set the objects's instance data */
foreach($row as $key => $value)
{
$obj->{$key} = $value;
}
return $obj;
}
class CPerson
{
function getFullName()
{
return $this->fname . ' ' . $this->lname;
}
}
$set = mysql_query('SELECT fname,lname FROM person');
while($person =& db_fetch_object($set,'CPerson'))
{
echo $person->getFullName();
}
When using table joins in a query you obviously need to name all the fields to make it work right with mysql_fetch_object().
an addition to the previous...
for example getting members from a database:
function getAllMembers () {
$query = "SELECT * FROM people ORDER BY lname";
$result = mysql_query($query);
while($member = mysql_fetch_object($result)){
$members[] = $member;
}
return $members;
}
<br><br>
DON'T FORGET TO DECLARE THE ARRAY. If you try to cycle through members after the function has been called and you don't declare the array first you will get a horribly (HORRIBLY!) ugly error in your page. Also, if you try to add the object into the members array inside the while condition instead of in the while loop, you will generate one extra empty space in the array due to the last iteration/check.
This is probably a little more elegant:
$sql = "SELECT * FROM table ";
$result = mysql_query($sql);
$data = array();
while ($row = mysql_fetch_object($result))
$data[] = $row;
I found the above code to be buggy, not adding all the records to the array. This is the code I used instead:
$command = "SELECT * FROM table ";
$result = mysql_query($command, $link_id);
$num = mysql_num_rows($result);
$clickthru = array();
for ($i = 0; $i <= $num; $i++) {
$clickthru[$i] = array();
$clickthru[$i] = mysql_fetch_array($result);
}
Allen
Be carefull:
the object returned will be a new/fresh object.
You can't use this function to replace some attributes of an existing object keeping the old ones.
Example:
class person
{
var $name;
var $surname;
var $doh;
function print()
{
print($name." ".$surname);
}
function get_from_db()
{
$res=query("select name, surname from ppl where... limit 1");
$this=mysql-fetch-object($res);
}
}
This won't work! When the method get_from_db() is executed, your old object will be destroyed... you won't find anything in the attribute $doh, and if you'll try to call the method print(), it will say it doesn't exist.