PDO is a major feature of PHP 5, because before PHP 5 php4/php3 are a bunch of database extensions to connect and process with each database, what Php_mysql.dll, Php_pgsql.dll, Php_mssql.dll, Php_ Sqlite.dll and so on to connect MySQL, PostgreSQL, MS SQL Server, SQLite, we must, by virtue of ADOdb, PEAR::D B, Phplib: Database abstract classes such as:D B to help us, extremely cumbersome and inefficient , after all, how efficient the PHP code can we write directly with C + + the expansion slope of high pinch? Therefore, the emergence of PDO is inevitable, we have to calm the attitude of learning to accept the use, perhaps you will find that you can reduce a lot of kung fu Oh.
Install PDO
I am on the Windows XP SP2, so, the whole process is in the Windows line, as for Linux/freebsd platform, please find the data setup.
I'm PHP 5.1.4, already with the Php_pdo.dll extensions, but need a little setup to use.
Open C:\windows\php.ini, that's my PHP profile, and find the following line:
Extension_dir
This is the directory where we expand, and my PHP 5 extension is: C:\php5\ext, so I'll change the line to:
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Extension_dir = "C:/php5/ext"
And then find it below the php.ini:
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; Dynamic Extensions;
Here's a bunch of similar, extension=php_mbstring.dll stuff, and here's the PHP extension load configuration, and we're going to add our PDO extensions on the last side:
Extension=php_pdo.dll
Extension=php_pdo_mysql.dll
Extension=php_pdo_pgsql.dll
Extension=php_pdo_sqlite.dll
Extension=php_pdo_mssql.dll
Extension=php_pdo_odbc.dll
Extension=php_pdo_firebird.dll
; Extension=php_pdo_oci8.dll
A variety of PDO drivers, can be added to the full plus, but the back of the Php_pdo_oci8.dll, because I did not install the Oralce database, so without this, use a semicolon to annotate it. Then restart our web server, Iis/apache, my IIS, hey, table despise me, on windows, simple. After restarting, write a phpinfo.php file in the document directory of our Web server, plus these:
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The output of the content, if you can see smoothly:
Pdo
PDO Support Enabled
PDO drivers MySQL, Pgsql, SQLite, MSSQL, ODBC, Firebird
There are a variety of driver instructions behind: Pdo_firebird,pdo_mssql,pdo_mysql,pdo_odbc,pdo_pgsql,pdo_sqlite. Well, congratulations on your installation success, otherwise please check the above steps carefully.
PDO Tutorial
I use MySQL 4.0.26, but I personally recommend that you use MySQL 4.1.x or MySQL 5.0.x, because those editions have a lot of interesting things worth learning. We PDO need to connect here is my MySQL 4.0, if you do not install MySQL, please install yourself. We built MySQL and added table foo to the test library, including four fields such as Id,name,gender,time.
We started constructing the first PDO application, creating a pdo.php file in the Web document directory:
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<?php
$DSN = "Mysql:host=localhost;dbname=test";
$db = new PDO ($dsn, ' root ', ');
$count = $db->exec (INSERT into foo SET name = ' Heiyeluren ', gender= ' man ', Time=now ());
Echo $count;
$DB = null;
?>
$DSN = "Mysql:host=localhost;dbname=test";
is to construct our DSN (data source), to see the information included: the database type is MySQL, the host address is localhost, the database name is test, so a few information. The data sources in different databases are constructed differently.
$db = new PDO ($dsn, ' root ', ');
Initializes a PDO object, the constructor's arguments the first one is our data source, the second is the user connecting to the database server, and the third parameter is the password. We can not guarantee the success of the connection, we will talk about the exception later, here we think it is connected successfully.
$count = $db->exec (INSERT into foo SET name = ' Heiyeluren ', gender= ' man ', Time=now ());
Echo $count;
Call our successful PDO object to execute a query that inserts a record and uses the Pdo::exec () method to return a result that affects the record, so we output the result. Finally, you need to end the object resource:
$DB = null;
The default is not a long connection, and if you need a database long connection, you need to add a final parameter: Array (pdo::attr_persistent => true) to this:
$db = new PDO ($dsn, ' root ', ' ", Array (pdo::attr_persistent => true));
One operation is so simple, perhaps not much different from the previous, and ADODB is somewhat similar.
PDO Advanced Tutorials
If we want to extract data, then we should use the data acquisition function. (The $db used below are the objects that are already connected above)
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<?php
foreach ($db->query ("SELECT * from foo")) {
Print_r ($row);
}
?>
We can also use this method of obtaining:
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<?php
$rs = $db->query ("SELECT * from foo");
while ($row = $rs->fetch ()) {
Print_r ($row);
}
?>
If you want to get all the data in an array at once, you can do this:
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<?php
$rs = $db->query ("SELECT * from foo");
$result _arr = $rs->fetchall ();
Print_r ($result _arr);
?>
The results of the output are as follows:
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Array
([0] => Array (
[ID] => 1
[0] => 1
[Name] => Heiyeluren
[1] => Heiyeluren
[Gender] => male
[2] => Male
[Time] => 2006-10-28 23:14:23
[3] => 2006-10-28 23:14:23
)
}
We look inside the records, the digital index and the associated index all have, waste resources, we only need to associate the index:
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<?php
$db->setattribute (Pdo::attr_case, Pdo::case_upper);
$rs = $db->query ("SELECT * from foo");
$rs->setfetchmode (PDO::FETCH_ASSOC);
$result _arr = $rs->fetchall ();
Print_r ($result _arr);
?>
Look at the code above, the SetAttribute () method is to set some properties, the main properties are: Pdo::attr_case, Pdo::attr_errmode, and so on, we need to set up here is Pdo::attr_case, When we use the associated index to get the dataset, the associated index is uppercase or lowercase, and there are several options:
Pdo::case_lower--Forcing the column name to be lowercase
Pdo::case_natural--column names in the original way
Pdo::case_upper--Force column name to uppercase
We use the Setfetchmode method to set the type to get the return value of the result set, as well as the same type:
PDO::FETCH_ASSOC--Associative array form
Pdo::fetch_num--Digital indexed array form
Pdo::fetch_both--both array forms are available, which is the default
Pdo::fetch_obj-Similar to previous mysql_fetch_object () in the form of objects
Of course, in general we are using PDO::FETCH_ASSOC, specifically using what, according to your own needs, other get type reference manuals.
In addition to this way of getting the data, there is this:
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<?php
$rs = $db->prepare ("SELECT * from foo");
$rs->execute ();
while ($row = $rs->fetch ()) {
Print_r ($row);
}
?>
Actually, it's almost. If you want to obtain a field result in a specified record, you can use Pdostatement::fetchcolumn ():
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<?php
$rs = $db->query ("SELECT COUNT (*) from foo");
$col = $rs->fetchcolumn ();
Echo $col;
?>
It is generally good to use Fetchcolumn () for Count statistics or some records that require only a single field.
A simple summary
Query operations are mainly Pdo::query (), Pdo::exec (), PDO::p repare (). Pdo::query () is used primarily for operations that have record results returned, especially select operations, where the pdo::exec () is primarily for operations returned without a result set, such as INSERT, UPDATE, delete, which returns the number of columns affected by the current operation. PDO::p repare () is mainly preprocessing operations, the need to $rs->execute () to perform preprocessing of the SQL statements, this method can be binding parameters, powerful, not this article can be simple to say, you can refer to the manual and other documents. Get result set operations mainly: Pdostatement::fetchcolumn (), Pdostatement::fetch (), Pdostatement::fetchall (). Pdostatement::fetchcolumn () is a field that gets the result to specify the first record, and the default is the first field. Pdostatement::fetch () is used to get a record, Pdostatement::fetchall () is to get all the recordset into one, and the results can be obtained through Pdostatement:: Setfetchmode to set the type that requires the result collection.
In addition there are two peripheral operations, one is Pdo::lastinsertid () and Pdostatement::rowcount (). Pdo::lastinsertid () is the last self-increasing ID that returns the last insert operation, and the primary key column type is the increment. Pdostatement::rowcount () is primarily used for pdo::query () and PDO::p Repare () The result set that is affected by the delete, INSERT, and update operations, to Pdo::exec () Method and select operation are not valid.
From the use above, I see that the PDO function is really powerful, and there are some things I did not talk about, such as binding parameters, preprocessing, stored procedures, transactions, and so on. There are different data to expand the DSN structure, the Oracle database itself a lot of special things, need to go deep to learn to understand, this article is just a simple description of some introductory knowledge, is a simple understanding of PDO.
