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(PHP 5)
mysqli_stmt::bind_result -- mysqli_stmt_bind_result — Binds variables to a prepared statement for result storage
Objektorientierter Stil
Prozeduraler Stil
Binds columns in the result set to variables.
When mysqli_stmt_fetch() is called to fetch data, the MySQL client/server protocol places the data for the bound columns into the specified variables var1, ....
Hinweis:
Note that all columns must be bound after mysqli_stmt_execute() and prior to calling mysqli_stmt_fetch(). Depending on column types bound variables can silently change to the corresponding PHP type.
A column can be bound or rebound at any time, even after a result set has been partially retrieved. The new binding takes effect the next time mysqli_stmt_fetch() is called.
Nur bei prozeduralem Aufruf: ein von mysqli_stmt_init() zurückgegebenes Statementobjekt.
The variable to be bound.
Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.
Beispiel #1 Objektorientierter Stil
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* prepare statement */
if ($stmt = $mysqli->prepare("SELECT Code, Name FROM Country ORDER BY Name LIMIT 5")) {
$stmt->execute();
/* bind variables to prepared statement */
$stmt->bind_result($col1, $col2);
/* fetch values */
while ($stmt->fetch()) {
printf("%s %s\n", $col1, $col2);
}
/* close statement */
$stmt->close();
}
/* close connection */
$mysqli->close();
?>
Beispiel #2 Prozeduraler Stil
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (!$link) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* prepare statement */
if ($stmt = mysqli_prepare($link, "SELECT Code, Name FROM Country ORDER BY Name LIMIT 5")) {
mysqli_stmt_execute($stmt);
/* bind variables to prepared statement */
mysqli_stmt_bind_result($stmt, $col1, $col2);
/* fetch values */
while (mysqli_stmt_fetch($stmt)) {
printf("%s %s\n", $col1, $col2);
}
/* close statement */
mysqli_stmt_close($stmt);
}
/* close connection */
mysqli_close($link);
?>
The above examples will output:
AFG Afghanistan ALB Albania DZA Algeria ASM American Samoa AND Andorra
If I have a longtext field in the result, the whole page will go blank, without giving me any errors what so ever. This is because PHP _crashes_. I've spent an entire morning figuring this out.
Apparently, if you have longtext present, you HAVE to call store_result before using bind_result.
http://bugs.php.net/bug.php?id=47928
Please note that if you have a column in the database with data type "Longtext" the bind_result will return an empty result for that column. It took me 5 days to figure it out!
If done properly, 'call_user_func_array()' works to bind variables to a result of multiple columns including BLOB columns.
EXAMPLE:
<?php
$data = array() ; // Array that accepts the data.
$params = array() ; // Parameter array passed to 'bind_result()'
$column = array("fidentity", "fvarchar", "fdate", "ftinyblob") ; // The column names.
foreach($column as $col_name)
{
// 'fetch()' will assign fetched value to the variable '$data[$col_name]'
$params[] =& $data[$col_name] ;
}
$res = call_user_func_array(array($stmt, "bind_result"), $params) ;
?>
Here's the complete example.
WARNING: When using 'prepare' to prepare a statement to retrieve LOBs the method order matters.
Also, method 'store_result()' must be called and be called in correct order.
Failure to observe this causes PHP/MySQLi to crash or return an erroneous value.
The proper procedure order is: prepare -> execute -> store_result -> bind -> fetch
<?php
$database = "test" ;
$table = "test" ;
$column = array("fidentity", "fvarchar", "fdate", "ftinyblob") ;
$select_set = "`fidentity`, `fvarchar`, `fdate`, `ftinyblob`" ;
$mysqli = new mysqli("localhost", "root", $password, $database);
// Proper procedure order: prepare -> execute -> store_result -> bind -> fetch
$stmt = $mysqli->prepare("SELECT $select_set FROM `$table`") ;
$stmt->execute();
$stmt->store_result();
$data = array() ; // Array that accepts the data.
$params = array() ; // Parameter array passed to 'bind_result()'
foreach($column as $col_name)
{
// Assign the fetched value to the variable '$data[$name]'
$params[] =& $data[$col_name] ;
}
$res = call_user_func_array(array($stmt, "bind_result"), $params) ;
if(! $res)
{
echo "bind_result() failed: " . $mysqli->error . "\n" ;
}
else
{
$res = $stmt->fetch() ;
if($res)
{
echo "<pre>" . htmlentities(print_r($data, true)) . "</pre>\n" ;
}
else
{
echo ((false !== $res) ? "End of data" : $stmt->error) . "\n" ;
}
}
$stmt->close() ;
$mysqli->close() ;
exit ;
?>
The above example should output:
Array (
[fidentity] => 24
[fvarchar] => the rain in spain
[fdate] => 2010-07-31
[ftinyblob] => GIF89a...(more BLOB data)
)
I discovered this one by accident; mysqli_stmt_bind_result overwrites an *existing* session variable of the same name (but doesn't create them).
In other words,
mysqli_stmt_bind_result($stmt, $col1, $col2);
will overwrite session variables $_SESSION['col1'] and $_SESSION['col2'] if they exist, but will not create them if they don't.
A note to people to want to return an array of results - that is, an array of all the results from the query, not just one at a time.
<?php
// blah blah...
call_user_func_array(array($mysqli_stmt_object, "bind_result"), $byref_array_for_fields);
$results = array();
while ($mysqli_stmt_object->fetch()) {
$results[] = $byref_array_for_fields;
}
?>
This will NOT work. $results will have a bunch of arrays, but each one will have a reference to $byref.
PHP is optimizing performance here: you aren't so much copying the $byref array into $results as you are *adding* it. That means $results will have a bunch of $byrefs - the same array repeated multiple times. (So what you see is that $results is all duplicates of the last item from the query.)
hamidhossain (01-Sep-2008) shows how to get around that: inside the loop that fetches results you also have to loop through the list of fields, copying them as you go. In effect, copying everything individually.
Personally, I'd rather use some kind of function that effectively duplicates an array than write my own code. Many of the built-in array functions don't work, apparently using references rather than copies, but a combination of array_map and create_function does.
<?php
// blah blah...
call_user_func_array(array($mysqli_stmt_object, "bind_result"), $byref_array_for_fields);
// returns a copy of a value
$copy = create_function('$a', 'return $a;');
$results = array();
while ($mysqli_stmt_object->fetch()) {
// array_map will preserve keys when done here and this way
$results[] = array_map($copy, $byref_array_for_fields);
}
?>
All these problems would go away if they just implemented a fetch_assoc or even fetch_array for prepared statements...
Took some cool code from here and made a little class for those object oriented kind of guys
used like this:
<?php
// execute prepared statement
$stmt->execute();
$stmt->store_result();
//custom class :D bind to Statement Result mambo jambo!
$sr = new Statement_Result($stmt);
$stmt->fetch();
printf("ID: %d\n", $sr->Get('id') );
/////////////////////////////////
class Statement_Result
{
private $_bindVarsArray = array();
private $_results = array();
public function __construct(&$stmt)
{
$meta = $stmt->result_metadata();
while ($columnName = $meta->fetch_field())
$this->_bindVarsArray[] = &$this->_results[$columnName->name];
call_user_func_array(array($stmt, 'bind_result'), $this->_bindVarsArray);
$meta->close();
}
public function Get_Array()
{
return $this->_results;
}
public function Get($column_name)
{
return $this->_results[$column_name];
}
}
?>
bind_ result can also be used to return an array of variables from a function,
This took me a long time to figure out, so I would like to share this.
<?php
function extracting(){
$query="SELECT topic, detail, date, tags
FROM updates
ORDER BY date DESC
LIMIT 5 ";
if($stmt = $this->conn->prepare($query)) {
$stmt->execute();
$stmt->bind_result($updates[0],$updates[1],$updates[2],$updates[3]);
$i=0;
while($stmt->fetch()){
$i++;
$name='t'.$i;
$$name = array($updates[0],$updates[1],$updates[2],$updates[3]);
}
return array($t1,$t2,$t3,$t4,$t5,);
$stmt->close();
}
}
?>
lot of people don't like how bind_result works with prepared statements! it requires you to pass long list of parameters which will be loaded with column value when the function being called.
To solve this, i used call_user_func_array function and result_metadata functions. which make easy and automatically returns an array of all columns results stored in an array with column names.
please don't forget to change setting variables with your own credentials:
<?php
$host = 'localhost';
$user = 'root';
$pass = '1234';
$data = 'test';
$mysqli = new mysqli($host, $user, $pass, $data);
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
if ($stmt = $mysqli->prepare("SELECT * FROM sample WHERE t2 LIKE ?")) {
$tt2 = '%';
$stmt->bind_param("s", $tt2);
$stmt->execute();
$meta = $stmt->result_metadata();
while ($field = $meta->fetch_field())
{
$params[] = &$row[$field->name];
}
call_user_func_array(array($stmt, 'bind_result'), $params);
while ($stmt->fetch()) {
foreach($row as $key => $val)
{
$c[$key] = $val;
}
$result[] = $c;
}
$stmt->close();
}
$mysqli->close();
print_r($result);
?>
Although inspired by an earlier post, this method could be added to any of your database objects. It's an object oriented implementation of an earlier post.
The method returns an array with objects representing a row. Each property represents a column and its value.
<?php
private function getresult($stmt)
{
$result = array();
$metadata = $stmt->result_metadata();
$fields = $metadata->fetch_fields();
for (;;)
{
$pointers = array();
$row = new stdClass();
$pointers[] = $stmt;
foreach ($fields as $field)
{
$fieldname = $field->name;
$pointers[] = &$row->$fieldname;
}
call_user_func_array(mysqli_stmt_bind_result, $pointers);
if (!$stmt->fetch())
break;
$result[] = $row;
}
$metadata->free();
return $result;
}
?>
I've created these functions which will act like mysqli_fetch_array() and mysqli_fetch_object() but work with bound results.
<?php
function fetch_object() {
$data = mysqli_stmt_result_metadata($this->stmt);
$count = 1; //start the count from 1. First value has to be a reference to stmt.
$fieldnames[0] = &$this->stmt;
$obj = new stdClass;
while ($field = mysqli_fetch_field($data)) {
$fn = $field->name; //get all the feild names
$fieldnames[$count] = &$obj->$fn; //load the fieldnames into an object..
$count++;
}
call_user_func_array(mysqli_stmt_bind_result, $fieldnames);
mysqli_stmt_fetch($this->stmt);
return $obj;
}
function fetch_array() {
$data = mysqli_stmt_result_metadata($this->stmt);
$count = 1; //start the count from 1. First value has to be a reference to the stmt. because bind_param requires the link to $stmt as the first param.
$fieldnames[0] = &$this->stmt;
while ($field = mysqli_fetch_field($data)) {
$fieldnames[$count] = &$array[$field->name]; //load the fieldnames into an array.
$count++;
}
call_user_func_array(mysqli_stmt_bind_result, $fieldnames);
mysqli_stmt_fetch($this->stmt);
return $array;
}
?>
Hope this helps some people, I was puzzled by this for a while.
If you select LOBs use the following order of execution or you risk mysqli allocating more memory that actually used
1)prepare()
2)execute()
3)store_result()
4)bind_result()
If you skip 3) or exchange 3) and 4) then mysqli will allocate memory for the maximal length of the column which is 255 for tinyblob, 64k for blob(still ok), 16MByte for MEDIUMBLOB - quite a lot and 4G for LONGBLOB (good if you have so much memory). Queries which use this order a bit slower when there is a LOB but this is the price of not having memory exhaustion in seconds.
Hi
I saw a bit of discussion about using mysqli_stmt_bin_result dynamically, without knowing exactly how many columns will be returned.
After a while i developed this snippet to mimic the same behaviour as mysql_fetch_array():
<?php
# of fields in result set.
$nof = mysqli_num_fields( mysqli_stmt_result_metadata($handle) );
# The metadata of all fields
$fieldMeta = mysqli_fetch_fields( mysqli_stmt_result_metadata($handle) );
# convert it to a normal array just containing the field names
$fields = array();
for($i=0; $i < $nof; $i++)
$fields[$i] = $fieldMeta[$i]->name;
# The idea is to get an array with the result values just as in mysql_fetch_assoc();
# But we have to use call_user_func_array to pass the right number of args ($nof+1)
# So we create an array:
# array( $stmt, &$result[0], &$result[1], ... )
# So we get the right values in $result in the end!
# Prepare $result and $arg (which will be passed to bind_result)
$result = array();
$arg = array($this->stmt);
for ($i=0; $i < $nof; $i++) {
$result[$i] = '';
$arg[$i+1] = &$result[$i];
}
call_user_func_array ('mysqli_stmt_bind_result',$arg);
# after mysqli_stmt_fetch(), our result array is filled just perfectly,
# but it is numbered (like in mysql_fetch_array() ), not indexed by field name!
# If you just want to mimic that ones behaviour you can stop here :)
mysqli_stmt_fetch($this->stmt);
# Now you can use $result
print_r($result);
# But beware! when using the fetch in a loop, always COPY $result or else you might
# end with all the same values because of the references
?>
Hope that this will help someone....
Matt
A potential problem exists in binding result parameters from a prepared statement which reference large datatypes like mediumblobs. One of our database tables contains a table of binary image data. Our largest image in this table is around 50Kb, but even so the column is typed as a mediumblob to allow for files larger than 64Kb. I spent a frustrating hour trying to figure out why mysqli_stmt_bind_result choked while trying to allocate 16MB of memory for what should have been at most a 50Kb result, until I realized the function is checking the column type first to find out how big a result _might_ be retrieved, and attempting to allocate that much memory to contain it. My solution was to use a more basic mysqli_result() query. Another option might have been to retype the image data column as blob (64Kb limit).
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