search
HomeBackend DevelopmentPHP Tutorialpdo usage study notes_PHP tutorial

pdo usage study notes_PHP tutorial

Jul 13, 2016 pm 04:55 PM
dataobjectpdophponeforbasic conceptstudydefinitionExpandusageofnotesClass libraryabbreviation

1. Basic concepts

1. PDO: Abbreviation of PHP Data Object. The PDO extension class library defines a lightweight, consistent interface for PHP, which provides a data access abstraction layer so that no matter what database is used, queries and data can be obtained through consistent functions.

PDO is a "database access abstraction layer" that unifies the access interfaces of various databases.

2. Operations on any database are not performed using the PDO extension itself, and must be accessed using specific PDO drivers for different database servers. Such as: MYSQL (PDO_MYSQL). A list of PDO parts can be viewed in the phpinfo() function.

2. PDO installation

1. Linux: When installing PHP, add the following flag to the configure command:

–with-pdo-mysql=/usr/local/mysql       ///usr/local/mysql is the mysql installation directory

2. Windows:

Find the php.ini file under C:windows

(1) Open: extension=php_pdo.dll

(2) Open: extension=php_pdo_mysql.dll

3. Using PDO process

1. Connect to database

(1) Create PDO object

(2) Set PDO behavior attributes (setattribute())

(3) Set character set ($link->query(‘set names UTF8’))

2. Send SQL statement

(1) Prepare SQL statement

(2) Execute sending

3. View results

4. Connect to database

1. Create PDO object:

(1)$link = new PDO(DSN, username, password, driver properties);

1) DSN: Data source name, used to define a driver that must be used and the database to be used. DSN format of mysql: ‘mysql:host=localhost;dbname=lamp30’

2) You can put the DSN in a file, such as: 'uri:file:///usr/local/dsn.txt'

3) Use the try...catch statement when creating an object, because when an error occurs when declaring a PDO instance, an exception will be automatically thrown. Such as:

The code is as follows Copy code
 代码如下 复制代码

try{

$link = new PDO(‘mysql:host=localhost;dbname=lamp30’,’root’,’111111’);

}catch(PDOException $e){

echo $e->getMessage();

exit(‘连接数据库错误.’);

}

try{

$link = new PDO(‘mysql:host=localhost;dbname=lamp30’,’root’,’111111’);

}catch(PDOException $e){

echo $e->getMessage();

exit(‘Error connecting to database.’);

}

2. Driver attributes

(1) You can pass the necessary options into an array (attribute name as element key, attribute value as element value) to the fourth parameter of the constructor. If the driver attribute is not defined in the constructor, you can later use the setattribute() function of the PDO class to define each attribute.

(2) There are Chinese explanations of these attributes on page P501 of the book.

3. Set character set: $link->query(‘set names UTF8’)

5. Send SQL statement

(1) $link->exec(): Execute additions, deletions, and modifications, and return the number of affected rows. If execution fails, return false or 0.

(2) $link->query(): Execute the query and return the PDOStatement result set object.

6. Query results

1. Non-query:
 代码如下 复制代码

$stmt = $link->prepare(‘select * from user where id=:id’);

$stmt->bindparam(‘:id’, $id, PDO::PARAM_INT);

$id = 2;

$stmt->execute();

(1) Directly use the number of rows affected by the return of $link->exec() (2)$link->lastInsertId() returns the AUTO_INCREMENT number value generated by the last INSERT command 2. See preprocessing 7. Preprocessing 1. Step 2: Send SQL statement
The code is as follows Copy code
$stmt = $link->prepare(‘select * from user where id=:id’); $stmt->bindparam(‘:id’, $id, PDO::PARAM_INT); $id = 2; $stmt->execute();

bindParam() parameters have the following 7 types: you don’t need to write

PDO::PARAM_INT

PDO::PARAM_STR

PDO::PARAM_BOOL

PDO::PARAM_NULL

PDO::PARAM_LOB: Large Object Data Type

PDO::PARAM_STMT: PDOstatement type

PDO::PARAM_INPUT_OUTPUT: Data type used by stored procedures

2. Step 3:

For example:

The code is as follows Copy code
 代码如下 复制代码

$stmt = $link->query(‘select * from user’);

(1)fetch()方法

$pdoStat ->bindColumn(1, $id);                 //第一个参数可以是从1开始的索引值

$pdoStat ->bindColumn(‘name’, $name);    //也可以是列名

$pdoStat ->bindColumn(‘pass’, $pass);

while($row = $stmt ->fetch(PDO::FETCH_BOUND)){

echo $id.’ ’;

echo $name.’ ’;

echo $pass.’
’;

}

$stmt = $link->query(‘select * from user’);

(1) fetch() method

$pdoStat ->bindColumn(1, $id); //The first parameter can be an index value starting from 1

$pdoStat ->bindColumn(‘name’, $name); //It can also be a column name
 代码如下 复制代码

$result = $stmt ->fetchall();

foreach($result as $row){

echo $row[‘id’].’ ’;

echo $row[‘name’].’ ’;

echo $row[‘pass’].’
’;

}

$pdoStat ->bindColumn(‘pass’, $pass);

while($row = $stmt ->fetch(PDO::FETCH_BOUND)){

echo $id.’ ’;

echo $name.’ ’;

echo $pass.’
’;

}

There are six types of fetch() parameters: see the manual.

 代码如下 复制代码

$link = new PDO(‘mysql:host=localhost;dbname=lamp30’);

//1

$link->setattribute(PDO::ATTR_AUTOCOMMIT, false);

//2

$link->begintransaction();

$result = $link->exec(‘insert into user(name,paa) values(‘wsy’,’111’)’);

//3

if($result){

$link->commit();

}else{

$link->rollback();

}

//4

$link->setattribute(PDO::ATTR_AUTOCOMMIT, true);

You can use the setFetchMode() method to set the default mode. (2) fetchall() method
The code is as follows Copy code
$result = $stmt ->fetchall(); foreach($result as $row){ echo $row[‘id’].’ ’; echo $row[‘name’].’ ’; echo $row[‘pass’].’
’; }
Fetchall() parameters are the same as fetch(). 8. Transaction processing 1. Turn off automatic submission (modify in driver properties) 2. Open transaction 3. Commit transaction/rollback 4. Turn on automatic submission For example:
The code is as follows Copy code
$link = new PDO(‘mysql:host=localhost;dbname=lamp30’); //1 $link->setattribute(PDO::ATTR_AUTOCOMMIT, false); //2 $link->begintransaction(); $result = $link->exec(‘insert into user(name,paa) values(‘wsy’,’111’)’); //3 if($result){ $link->commit(); }else{ $link->rollback(); } //4 $link->setattribute(PDO::ATTR_AUTOCOMMIT, true);

9. Member methods in PDO objects

1. $link->getattribute (attribute name): Get a driver attribute.

2. $link->setattribute (attribute name, attribute value): Set a driver attribute.

1) Because Oracle returns empty strings as NULL values, but other databases do not have this feature, in order to have better compatibility $link->setattribute(PDO::ATTR_ORACLE_NULLS,PDO::NULL_EMPTY_STRING,);

2) There are three ways to display errors: static, WARNING message, exception

3. $link->errorcode(): Get the error code.

1) If the setattribute function sets the error display mode to static, nothing will be displayed when an error occurs. This function must be called to view the error number.

4. $link->errorinfo(): Get error information (array).

1) If the setattribute function sets the error display mode to static, nothing will be displayed when an error occurs. This function must be called to view the error message.

5. $link->lastinsertid(): Get the primary key value of the last data inserted into the table (if multiple pieces of data are inserted at the same time, return the ID of the first inserted row).

6. $link->prepare(): Send the prepared SQL statement and return the PDOStatement object.

7. $link->begintransaction(): Open transaction.

8. $link->commit(): Submit a transaction and execute a SQL.

9. $link->rollback(): Roll back a transaction.

10. Error mode

1. Static mode:

The code is as follows
 代码如下 复制代码

$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT)

Copy code

$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT)

 代码如下 复制代码

$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING)

(1) Default mode, no operation is performed when an error occurs, PDO will only set the error code.

(2) To view errors, you can call errorCode() and errorInfo(). Both PDO and PDOStatement classes have these two methods.

2. Warning mode:

3. Abnormal mode:
The code is as follows
 代码如下 复制代码

$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION)

Copy code

$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING)

(1) In addition to setting the error code in this mode, PDO will also issue a PHP traditional E_WARNING message.
 代码如下 复制代码

$link->setAttribute(PDO::ATTR_PERSISTENT, true);

(2) This is the way mysql and mysqli display errors.

The code is as follows
Copy code
$link->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION) (1) In addition to setting the error code in this mode, PDO will also throw a PDOException and set its properties to reflect the error code and error information. (2) If an exception causes the script to terminate, the transaction will be automatically rolled back. (3) PDO recommends using this mode. 11. Persistent connection
The code is as follows Copy code
$link->setAttribute(PDO::ATTR_PERSISTENT, true); A persistent connection will not automatically disconnect when the script execution ends, and the connection cannot be closed using $link->close().

www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/631647.htmlTechArticle1. Basic concepts 1. PDO: Abbreviation of PHP Data Object. The PDO extension class library defines a lightweight, consistent interface for PHP, which provides a data access abstraction layer so that no matter...
Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How does PHP identify a user's session?How does PHP identify a user's session?May 01, 2025 am 12:23 AM

PHPidentifiesauser'ssessionusingsessioncookiesandsessionIDs.1)Whensession_start()iscalled,PHPgeneratesauniquesessionIDstoredinacookienamedPHPSESSIDontheuser'sbrowser.2)ThisIDallowsPHPtoretrievesessiondatafromtheserver.

What are some best practices for securing PHP sessions?What are some best practices for securing PHP sessions?May 01, 2025 am 12:22 AM

The security of PHP sessions can be achieved through the following measures: 1. Use session_regenerate_id() to regenerate the session ID when the user logs in or is an important operation. 2. Encrypt the transmission session ID through the HTTPS protocol. 3. Use session_save_path() to specify the secure directory to store session data and set permissions correctly.

Where are PHP session files stored by default?Where are PHP session files stored by default?May 01, 2025 am 12:15 AM

PHPsessionfilesarestoredinthedirectoryspecifiedbysession.save_path,typically/tmponUnix-likesystemsorC:\Windows\TemponWindows.Tocustomizethis:1)Usesession_save_path()tosetacustomdirectory,ensuringit'swritable;2)Verifythecustomdirectoryexistsandiswrita

How do you retrieve data from a PHP session?How do you retrieve data from a PHP session?May 01, 2025 am 12:11 AM

ToretrievedatafromaPHPsession,startthesessionwithsession_start()andaccessvariablesinthe$_SESSIONarray.Forexample:1)Startthesession:session_start().2)Retrievedata:$username=$_SESSION['username'];echo"Welcome,".$username;.Sessionsareserver-si

How can you use sessions to implement a shopping cart?How can you use sessions to implement a shopping cart?May 01, 2025 am 12:10 AM

The steps to build an efficient shopping cart system using sessions include: 1) Understand the definition and function of the session. The session is a server-side storage mechanism used to maintain user status across requests; 2) Implement basic session management, such as adding products to the shopping cart; 3) Expand to advanced usage, supporting product quantity management and deletion; 4) Optimize performance and security, by persisting session data and using secure session identifiers.

How do you create and use an interface in PHP?How do you create and use an interface in PHP?Apr 30, 2025 pm 03:40 PM

The article explains how to create, implement, and use interfaces in PHP, focusing on their benefits for code organization and maintainability.

What is the difference between crypt() and password_hash()?What is the difference between crypt() and password_hash()?Apr 30, 2025 pm 03:39 PM

The article discusses the differences between crypt() and password_hash() in PHP for password hashing, focusing on their implementation, security, and suitability for modern web applications.

How can you prevent Cross-Site Scripting (XSS) in PHP?How can you prevent Cross-Site Scripting (XSS) in PHP?Apr 30, 2025 pm 03:38 PM

Article discusses preventing Cross-Site Scripting (XSS) in PHP through input validation, output encoding, and using tools like OWASP ESAPI and HTML Purifier.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

MinGW - Minimalist GNU for Windows

MinGW - Minimalist GNU for Windows

This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools