MySQL connection in PHP can be established in two ways:
$mysql = new mysqli('localhost', 'user_name', 'password', 'database_name');
or
$link = mysqli_connect('localhost', 'user_name', 'password');
mysqli_set_charset($link, 'utf8');
mysqli_select_db($link, 'database_name');
Which one is the better and why?
Whichever one you prefer. I would go with the OOP Interface for consistency with the rest of my application, because that's how I use MySqli. Also, in my opinion, the OOP interface way is much cleaner (aesthetically, at least).
The best way to connect to MySQL database in PHP is using PDO driver. PDO offers you parameterized query that lets you avoid SQL injection easily, and other features you may love. It is ready to work with object-oriented programming, which is pretty cool.
PDO also can be used to connect to other kinds of SQL databases, like SQL Server, etc. You have to learn PDO (it's simple) and then you can connect to many kinds of SQL databases.
Connecting using the mysqli extension gives you the ability to use newer MySQL features such as transactional queries and parameterised queries which aren't available using the older mysql extension.
Have a look at http://www.php.net/manual/en/book.mysqli.php
Will you be dealing with more than one database? If so it might be a good idea not to set the database_name in the constructor. Otherwise, no problem. Other than the fact that you set the charset in the second one I don't think there's much of a difference.
if (!function_exists('mysqli_init') && !extension_loaded('mysqli')) {
// error: mysqli extension error
exit('...');
}
$connection = mysqli_init();
#mysqli_real_connect($connection, DBHOST,
DBUSER, DBPASS, DBNAME, DBPORT, NULL, MYSQLI_CLIENT_FOUND_ROWS);
if (mysqli_connect_errno() > 0) {
// error: connection error
echo mysqli_connect_error();
exit();
}
// Force UTF-8.
mysqli_query($connection, 'SET NAMES "utf8"');
This sample according to Drupal6
database.mysqli.inc
Both approaches are valid ways to use the mysqli extension. The first is the object-oriented interface and the second is the procedural interface. They are equivalent and it is simply a matter of preference. See the PHP mysqli documentation.
Related
Connection file is as below
$host="localhost";
$username="root";
$password="123";
$database = "order";
$con = mysqli_connect($host, $username, $password, $database);
$sel_db=mysqli_select_db($con,$database) or die("Cannot Select Database");
In each file I include above connection file
My older code for mysql is like
mysql_query("select * from order_detail");
and new query for mysqli is as below
mysqli_query($con,"select * from order_detail");
Above query required $con for connection
and mysql_fetch_array($var) becomes mysqli_fetch_array($var) it does not required $con
mysql_real_escape_string($var) becomes mysql_real_escape_string($con,$var);
So my question is that which query required $con as connection
The mysql functions implicitly used the last connection that was made if no connection was explicitly given. Note that you already could pass in a connection, even to the old function as you can read here. This behavior is confusing and error prone, so fortunately they made that more explicit in the mysqli functions.
I'm not sure that is the main reason though. It probably might have more to do with the fact that mysqli also has an object syntax, and that one syntax wraps another. The $con variable in the procedural version and the object instance in the objective version both serve the same purpose: telling the function/method which connection to use. Actually, the doc says that the connection parameter for mysqli_query is a mysqli object instance, so mysqli_query might just be implemented like this as a wrapper function to make it easier to convert your code from mysql to mysqli:
function mysqli_query($link, $query, $resultmode = MYSQLI_STORE_RESULT) {
return $link->query($query, $resultmode);
}
If you didn't understand anything I said in this last paragraph, don't worry, it's not really important. ;)
Anyway, while mysql_query performs a query on a connection, mysql_fetch_array fetches values from a query result. The $var your pass to it already contains all the information it needs. It doesn't need a connection at that point, so there is no need to pass it as an argument. There is no mysqli_fetch_array by the way. Instead you should use mysqli_stmt_fetch, to which the same applies: it doesn't need a connection, but a statement object (mysqli_stmt), which represents the query result.
Many of the mysqli functions have the same or similar parameters as their predecessors, but there may be differences. So for every function you use, I'd check the official documentation.
And also, I'd use an IDE or editor that will help you with the function syntax by providing built in code insight. Netbeans for PHP is a quite elaborate one that can be used for free, but there are even better ones (like PHPStorm) if you can spend some money.
PS: If you use prepared statements, you can get rid of mysql_real_escape_string completely.
In the light of MySQL to soon be deprecated, I need to move a large website using ADODB from MySQL to MySQLi.
Now I have looked up a few topics on Stackoverflow and thanks to the community I already have a genral idea of what needs to be done. Best topics on the matter are those ones:
ADODB mySQLi Connection
Switch large website from MySQL to MySQLi
However, I do still need a bit more clarification on my particular case, where ADODB is being used.
This is what I use to connect to the DB:
define('DBHOST', 'db_host');
define('DBUSER', 'db_user');
define('DBPASS', 'db_pass');
define('DBNAME', 'db_name');
include('adodb/adodb.inc.php');
$db = ADONewConnection('mysql');
$db->Connect(DBHOST,DBUSER,DBPASS,DBNAME) or die("Database not found!");
So first I am changing:
$db = ADONewConnection('mysql');
to
$db = ADONewConnection('mysqli');
That's the easy part, I guess.
Now since I am using ADODB, do I also need to change all instances of MySQL_* functions to MySQLi_* or ADODB takes care of this automatically? I think I know the answer but anyhow have to ask.
My most common MySQL_ functions are:
mysql_insert_id()
mysql_query()
mysql_fetch_array()
mysql_num_rows()
mysql_escape_string()
mysql_connect()
mysql_select_db()
mysql_error()
Most common usage is like $variable = mysql_insert_id(); or $v1 = mysql_query($v);
Is there anything else I should take into consideration when moving from MySQL to MySQLi for ADODB?
"do I also need to change all instances of MySQL_* functions to MySQLi_* ?"
The answer is yes. Different MySQL APIs/functions do not intermix. You must use the same API/functions from connection to querying.
You can use the following functions, simply replacing mysql_ by mysqli_, while passing a database connection in functions that require it and as the first parameter.
I.e. mysqli_query($connection, $query).
They are marked with asterisks *.
mysqli_insert_id() - *
mysqli_query() - *
mysqli_fetch_array()
mysqli_num_rows()
mysqli_escape_string() - *
mysqli_connect() - *
mysqli_select_db() - *
mysqli_error() - *
Consult the manual http://php.net/manual/en/book.mysqli.php
1) I would suggest you to use pdo_mysql instead of mysql since it has better support for transactions.
2) ADODB initializes the driver being used (e.g. mysql or pdo_mysql) by using the dsn identifier from the connection string i.e. pdo_mysql://localhost/mydb or mysql://localhost/mydb.
Just switch mysql -> pdo_mysql in the connection string and it starts to use mysqli -driver instead.
3) Driver loading logic is located on row ~4860 at adodb.inc.php, and at least in the version I'm using from composer, there is no switch to be able to configure mysqli, but it upgrades mysql -> mysqli automatically if you have PHP 7.0.0 or higher. You could tweak this code to force mysqli also by adding one if-statement, but then you have a custom fork of ADODB. Maybe do a pull request.
case 'mysql':
// mysql driver deprecated since 5.5, removed in 7.0
// automatically switch to mysqli
if(version_compare(PHP_VERSION, '7.0.0', '>=')) {
$db = 'mysqli';
}
$class = $db;
break;
I have used mysql_query() throughout my project; but I've just learned that mysql_ was deprecated as of PHP 5.5, has been removed in PHP 7.
So, I would like to know if I can replace all mysql_ functions with mysqli_ in my project blindly? For example, just replacing mysql_query() with mysqli_query(). Is there any adverse effect?
The short answer is no, the functions are not equivalent.
The good news is there is a converter tool that will help you if you've got a lot of calls/projects to change. This will allow your scripts to work right away.
https://github.com/philip/MySQLConverterTool
It's a forked version of the Oracle original version, and it's kosher.
That said, it's not too difficult to update your code, and you might want to migrate to an object orientated methodology anyway ...
1) The Connection
For all intents and purposes, you need a new connection function that saves the connection as a PHP variable, for example;
$mysqli = new mysqli($host, $username, $password, $database);
Notice I've saved the connection to $mysqli. You can save to $db or whatever you like, but you should use this throughout your code to reference the connection.
Remember to enable error reporting for mysqli before opening the connection;
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
2) The Query
Note: You should protect against SQL injection with prepared statements, which are available in MySQLi. Take a look at How can I prevent SQL injection in PHP?, but I'm just going to cover the basics here.
You now have to include the connection as an argument in your query, and other mysqli_ functions. In procedural code it's the first argument, in OO you write it like a class method.
Procedural:
$result = mysqli_query($mysqli, $sql);
OO:
$result = $mysqli->query($sql);
3) Fetch Result
The fetching of the result is similar to the old mysql_ function in procedural;
while ($row = mysqli_fetch_assoc($result))
but as $result is now an object in mysqli, you can use the object function call;
while ($row = $result->fetch_assoc())
4) Close Connection
So as before, you need to include the connection in the close function; as an argument in procedural;
mysqli_close($mysqli);
and as the object that you run the function on in OO;
$mysqli->close();
I would be here forever if I went through them all, but you get the idea. Take a look at the documentation for more information. Don't forget to convert any connection close, result release, or error and row counting functions you have.
The basic rule of thumb is for functions that use the database connection, you need to include it in the function now (either as the first argument in procedural, or the object you use to call the function in OO), or for a result set you can just change the function to mysqli_ or use the result set as the object.
If you cannot convert all calls to the mysqli functions on a old project, you could install and include the library php7-mysql-shim.
It will try to create a transparent replacement for mysql on PHP 7 using mysqli.
Obviously the performance is slower, but it's a solution to get around the problem in a couple of minutes.
You may safely include the library in projects working with PHP 5.6 (it will be ignored).
if (defined('PHP_VERSION_ID') && (PHP_VERSION_ID >= 50600)) { require_once "mysql-shim.php"; }
You can't. some of the functions of mysql and mysqli require different parameters. So you should know which will use the same parameters.
There are three methods to connect to mysql from php. mysql_connect,mysqli,PDO.
Which is best one to use a stored procedure in my application?
Please guide me
mysqli is straightforwardly better than mysql. PDO has a lot of good things going for it. I have a codebase in which at the moment I use mysqli along with stored procedures, and I don't have any complaints.
PDO supports stored procedure calls. Good tutorial here
http://www.phpro.org/tutorials/Introduction-to-PHP-PDO.html
PHP PDO is the easiest way to go, it takes care of all the specifics.
http://php.net/manual/en/book.pdo.php
example:
$pdo = new PDO( <connection_data> );
$stat = $pdo->prepare('SELECT * FROM table WHERE id=?');
$ids = array(1,2,3);
foreach($ids as $id) {
$r = $stat->execute(array($id));
if($r===false) # something wrong
else while(($c = $stat->fetch())!==false) {
var_dump($c);
}
}
I think you should use pdo because it supports not only mysql but also several other databases like MSSQL, Oracle, IBM DB2, PostgreSQL etc. Here is a great tutorial on PDO.
Should I use php PDO or normal mysql_connect to execute database queries in PHP?
Which one is faster?
One of the big benefits of PDO is that the interface is consistent across multiple databases.
There are some cool functions for prepared statements too, which take some of the hassle out of escaping all your query strings. The portability of PDO is greater than mysql_connect.
So, should I use PDO for those reasons or stick to the traditional mysql_connect?
PDO is a bit slower than the mysql_*
But it has great portability. PDO provides single interface across multiple databases. That means you can use multiple DB without using mysql_query for mysql, mssql_query for MS sql etc. Just use something like $db->query("INSERT INTO...") always. No matter what DB driver you are using.
So, for larger or portable project PDO is preferable. Even zend framework use PDO.
Some quick timings indicate PDO is slightly faster at connecting.
$start = microtime(true);
for($i=0; $i<10000; ++$i) {
try {
$db = new PDO($dsn, $user, $password);
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage()."\n";
}
$db = null;
}
$pdotime = microtime(true) - $start;
echo "PDO time: ".$pdotime."\n";
$start = microtime(true);
for($i=0; $i<10000; ++$i) {
$db = mysql_connect($host, $user, $password);
if(!$db) {
echo "Connection failed\n";
}
if(!mysql_select_db($schema, $db)) {
echo "Error: ".mysql_error()."\n";
}
mysql_close($db);
}
$rawtime = microtime(true) - $start;
echo "Raw time: ".$rawtime."\n";
Gives results like
PDO time: 0.77983117103577
Raw time: 0.8918719291687
PDO time: 0.7866849899292
Raw time: 0.8954758644104
PDO time: 0.77420806884766
Raw time: 0.90708494186401
PDO time: 0.77484893798828
Raw time: 0.90069103240967
The speed difference will be negligible anyway; establishing a network connection will likely take a LOT longer than any overhead incurred by PDO, especially if the mysql server is on another host.
You mentioned all the reasons to use PDO yourself. Really, never use the mysql_* functions directly, either use PDO, or use some other library.
With PDO you can uses binded params and that will prevent most sql injection attacks.
You can gain more speed using PDO prepared statements.
standard interface to all db backends
There are a bunch of useful methods (like the fetch* family)
I don't think speed is what people are looking for when they are using PDO -- I don't know if there is a difference, and I honnestly don't care : as long as I'm doing a couple of queries to a database when generating a page, a couple of milliseconds on the PHP side will not change anything.
There are two/three great things with PDO, compared to mysql_* :
More or less constant interface accross databases ; better than using mysql_*, pg_*, oci_*, ...
Object-Oriented API (mysqli_* has an OO-API, but not mysql_*)
Support new features of MySQL >= 4.1 (same as mysqli_*, but not mysql_*, again)
BTW : I'm generally using PDO -- either "by hand", or as it's integrated in / used by Zend Framework and/or Doctrine.
As a sidenote : Even if you are not going to use PDO, note that using mysqli instead of mysql is recommended.
See this page of the PHP manual, about that.
I did some performance testing to compare Mysqli functions to PDO functions using both prepared statements and regular direct queries (tested using select statements on Mysqlnd and MyISAM tables).
I found that PDO queries are just slightly slower than Mysqli, but only slightly. This makes sense since PDO used for this purpose mostly just a wrapper that calls Mysqli functions. The advantage to using PDO is that it makes it a little easier to migrate to a different database because the function names aren't specific to MySQL.
The real performance difference is in whether you use prepared queries. There is a large and significant performance penalty to using prepared queries. Other people who have tested them have found the same results.
The only time prepared queries are faster is if you are preparing a query once and then submitting it thousands of times with different data values. Otherwise, it's always faster to use mysqli::query() or PDO::query(). But it's important to be aware that those functions don't escape data values for you, so you need to remember to use mysqli::real_ escape_ string() or PDO::quote() on data variables.
I would generally recommend using PDO unless there is a specific reason you cannot. If there is no little difference between the two and you have no reason not to use PDO, I believe it would be better to get into the practice of using DB abstraction in your applications than going with mysql_* simply because it is there. I would say let best practice win.
In both cases, you call the same mySQL server from the same Php server ... so you cannot notice a lot of difference.
If you want good performance, think about cache (memcache or simple Php file ...) and make a good data base structure (INDEX ...)
PDO is better than SQl
PDO And His Prepare Statement Provide Best Secure Code against SQL injection
PDO is Object Oriented ;)
PDO is compatible with some Databases Engine As Explained Before
MySQLl_* Is Deprecated and will be removed soon
PDO provide more functionality with less line of codes Example:
Pdo
Connect
Check for "<" And ">" And "#" (This check for global uses)
Prepare
Execute
Close
MySQL_*
Connect
Add Backslash
Xsafe
Check for "<" And ">" And "#" (This check for global uses)
Query
Close
both the same functionality but you compare for codes
PDO is more Humanly Readable :)
So what you think?
If performance isn't a "real problem" for you, you should use PDO. The performance differs by small margins, and PDO has a very nice and portable cross-database interface wich can save you some headaches in case you need to use several database drivers.
The mysql_connect function is deprecated as of PHP 5.5.0 and, as with most deprecated features, will be removed. Therefore, prefer using PDO_MySQL (or another alternative MySQLi ) over mysql_connect.
Source: http://php.net/manual/en/function.mysql-connect.php
Some Advantages of PDO:
Can Access multiple database.
Provided many database driver to connect with different different database.
When you switch from one database to another database, you need not to write all the code to connect with new database, just change the connection string and some query which are required for new database.
It provides prepare statement which is a kind of template of query which compiled only once and can be executed as many times as you want, by just changing the attributes which is called place-holder.
Easy and efficient General Operation like- Insert, update...etc.
PDO database connection code:
<?php
$dbhost = 'localhost';
$dbname = 'clsrepair';
$dbuser = 'root';
$dbpass = '';
try {
$db = new PDO("mysql:host={$dbhost};dbname={$dbname}",$dbuser,$dbpass);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch(PDOException $e) {
echo "Connection error: ".$e->getMessage();
}
?>
Normal MySQL database connection code:
<?php
mysql_connect("localhost","root", "");
mysql_select_db ("clsrepair");
?>
or
<?php
$dbHost = 'localhost'; // usually localhost
$dbUsername = 'root';
$dbPassword = '';
$dbDatabase = 'clsrepair';
$db = mysql_connect($dbHost, $dbUsername, $dbPassword) or die ("Unable to connect to Database Server.");
mysql_select_db ($dbDatabase, $db) or die ("Could not select database.");
?>
MySQL database connection code easy but PDO has many advantage.