One:
Php-mysql is PHP operation MySQL Database The most original Extension, php-mysqli I representative of improvement, to mention the relative advanced function, in the case of Extension, itself also increased security. and PDO (PHP data Object) is to provide a abstraction Layer to operate the database, in fact, can not see what the difference, so directly to see the program it ...
First, let's take a look at a code written in Php-mysql, which is commonly used around the world:
Copy Code code as follows:
<?php
Mysql_connect ($db _host, $db _user, $db _password);
mysql_select_db ($dn _name);
$result = mysql_query ("Select ' Name ' from ' Users ' WHERE ' location ' = ' $location '");
while ($row = Mysql_fetch_array ($result, MYSQL_ASSOC))
{
echo $row [' name '];
}
Mysql_free_result ($result);
?>
At first glance, there is no problem, but there is some learning behind it ...
This is not a way to Bind Column, which, in the case of previous SQL narratives, is easily injection by SQL. $location. Later, mysql_escape_string (note: 5.3.0) and mysql_real_escape_string () were developed to solve the problem, but the whole narrative became complex and ugly, and if there were more fields, Can imagine what would be the situation ...
Copy Code code as follows:
<?php
$query = sprintf ("SELECT * from Users WHERE user= '%s ' and password= '%s '")
Mysql_real_escape_string ($user),
Mysql_real_escape_string ($password));
mysql_query ($query);
?>
There has been a lot of progress in php-mysqli, in addition to solving the problem through Bind Column, and it also Transaction, Multi Query, and also provides an Object oriented style (the following section php-mysq Li example of the writing) and procedural style (above Php-mysql example) two ways to write ... Wait a minute.
Copy Code code as follows:
<?php
$mysqli = new Mysqli ($db _host, $db _user, $db _password, $db _name);
$sql = "INSERT into ' users ' (ID, name, gender, location) VALUES (?,?,?,?)";
$stmt = $mysqli->prepare ($sql);
$stmt->bind_param (' dsss ', $source _id, $source _name, $source _gender, $source _location);
$stmt->execute ();
$stmt->bind_result ($id, $name, $gender, $location);
while ($stmt->fetch ())
{
Echo $id. $name. $gender. $location;
}
$stmt->close ();
$mysqli->close ();
?>
But to see that there are some drawbacks, such as Bind result, this is a little extra, but it does not matter, because the biggest problem is that this is not an abstract (abstraction) method, so when the back-end to replace the database, it is the beginning of pain ...
So PDO appeared (note: At present, Ubuntu and Debian, PDO does not have a direct suite to install, but must be installed through the PECL).
Copy Code code as follows:
roga@carlisten-lx:~$ PECL Search PDO
=======================================
Package stable/(Latest) Local
PDO 1.0.3 (Stable) PHP Data Objects Interface.
PDO_4D 0.3 (Beta) PDO driver for 4d-sql database
Pdo_dblib 1.0 (Stable) Freetds/sybase/mssql driver for PDO
Pdo_firebird 0.2 (Beta) firebird/interbase 6 driver for PDO
PDO_IBM 1.3.2 (Stable) PDO driver for IBM databases
Pdo_informix 1.2.6 (Stable) PDO driver for IBM informix Informix databases
Pdo_mysql 1.0.2 (Stable) MYSQL driver for PDO
PDO_OCI 1.0 (Stable) Oracle call Interface driver for PDO
Pdo_odbc 1.0.1 (Stable) ODBC v3 Interface driver for PDO
Pdo_pgsql 1.0.2 (Stable) PostgreSQL driver for PDO
Pdo_sqlite 1.0.1 (Stable) SQLITE v3 Interface driver for PDO
Pdo_user 0.3.0 (Beta) userspace driver for PDO
When installed through the PECL installation, the database can be manipulated in the following ways:
Copy Code code as follows:
<?php
$DSN = "mysql:host= $db _host;dbname= $db _name";
$DBH = new PDO ($DSN, $db _user, $db _password);
$sql = "Select ' Name ', ' Location ' from ' Users ' WHERE ' location ' =?, ' name ' =?";
$sth = $dbh->prepare ($sql);
$sth->execute (Array ($location, $name));
$result = $sth->fetch (pdo::fetch_obj);
Echo $result->name. $result->location;
$DBH = NULL;
?>
At first glance, PDO's code seems to be no shorter, so what is the benefit?
1. PDO connects to the database by Connection String to determine which database to connect to.
2. PDO can pdo::setattribute to determine the connection settings, such as persistent Connection, return the wrong Way (Exception, e_warning, NULL). Even the case of the return field name ... Wait a minute.
2. PDO supports the Bind column function, in addition to the basic Prepare, Execute, can bind a single field, and specify the field type.
4. PDO is a abstraction Layer so it takes less effort to replace the storage medium.
Unfortunately, although these things have been there for a long time, but still not popular. I think it may be because people are accustomed to reading the books in the book, but those books tend to introduce the simplest and most traditional ways. This leads many people to use MySQL as a direct link to the database.
However, for the moment, I personally prefer to connect to the database through DBI, such as ActiveRecord and Propel ORM (Object-relational Mapping).
For example, take ActiveRecord as an example, if you want to implement such a SQL narration ...
INSERT into ' users ' (ID, name, gender, location) VALUES (1, ' Roga ', ' Male ', ' TPE ')
The PDO to write is:
Copy Code code as follows:
<?php
$sql = "INSERT into ' users ' (ID, name, gender, location) VALUES (?,?,?,?)";
$sth = $dbh->prepare ($sql);
$sth->execute (Array (1, ' Roga ', ' Male ', ' TPE '));
?>
But in the case of ActiveRecord, it is:
Copy Code code as follows:
<?php
$user = new User ();
$user->id = 1;
$user->name = ' Roga ';
$user->gender = ' male ';
$user->location = ' TPE ';
$user->save ();
?>
The latter is not a lot more concise in grammar, but also significantly reduce the dependence on the SQL language! (For SQL implementation problems with different repositories, refer to Comparison of different SQL implementations)
The above is some simple introduction, if there are omissions fallacy also welcome everyone to add.
MySQL is a non-holding relay function and MYSQLI is a permanent connection function. Other words
MySQL each link will open a connected process and mysqli run mysqli multiple times will use the same connection process, thereby reducing the cost of the server
Some friends use new mysqli (' localhost ', usenamer ', ' Password ', ' databasename ') when they are programmed;
Wrong, Fatal Error:class ' mysqli ' not found in d:\ ...
is the Mysqli class not PHP-led?
Not the default to open, win under to change php.ini, remove Php_mysqli.dll before, Linux to the mysqli compiled in.
One: Mysqli.dll is a way to manipulate the database in an object-or-process manner, and it is easy to use. Here is a comparison of several common operations with Mysql.dll.
1:mysql.dll (can be understood as a functional approach):
Copy Code code as follows:
$conn = mysql_connect (' localhost ', ' user ', ' password '); Connecting to the MySQL database
mysql_select_db (' data_base '); Select Database
$result = mysql_query (' select * from Data_base ');//Here is a second optional parameter that specifies an open connection
$row = Mysql_fetch_row ($result))//For simplicity, only one row of data is taken here
echo $row [0]; Output the value of the first field
Mysqli also has a process-style approach, but it starts with a mysqli prefix, all the same. If Mysqli is manipulated in a procedural way, some functions must specify resources, such as mysqli_query (resource identification, SQL statement), and resource identifier parameters are placed in front, while mysql_query (SQL statement, ' optional ') resource identification is placed behind , and can be unspecified, which defaults to the last open connection or resource.
2mysqli.dll (object mode):
Copy Code code as follows:
$conn = new mysqli (' localhost ', ' user ', ' password ', ' data_base ');
The connection here is new, and the last parameter is to specify the database directly, without mysql_select_db ().
can also be constructed without specifying, and then $conn-> select_db (' data_base ')
$result = $conn-> query (' SELECT * from Data_base ');
$row = $result-> fetch_row (); Fetch a row of data
Echo Row[0]; Output the value of the first field
Two: Mysql_fetch_row (), mysql_fetch_array ()
These two functions return an array, the difference being that the first function returns an array that contains only the values we can only $row[0],
$row [1], which reads the data as an array subscript, and mysql_fetch_array () returns an array that contains both the first and key values
On the form, we can read the data in this way (if the database field is USERNAME,PASSWD):
$row [' username '], $row [' passwd ']
Furthermore, if you use ($row as $kay => $value), you can also get the field name of the database directly.
More important, Mysqli is a new library of functions provided by PHP5, and (i) represents an improvement that performs faster.
