When using wordpress, if you want to directly use the database operation class (wp-db.php) encapsulated in WP, you can use it by including wp-blog-header.php in the code.
define(‘PATH’, dirname(dirname(__FILE__)).‘/’); require_once(PATH . ‘../wp-blog-header.php’); global $wpdb;
When inserting data, one of the methods is to use the insert() function in the wp-db class.
$table = "test_table"; $data_array = array( ‘column_1′ => ‘data1′, ‘column_2′ => ‘data2′ ); $wpdb->insert($table,$data_array);
The first parameter is the name in the database table, and the second parameter is the data to be inserted, which is an array. The name of the key in the array is the column name in the table. In fact, the insert() function also has a third parameter format. Interested friends can check in the method definition of wp-db.php. When updating data, you can use the update() function, for example:
$table = "test_table"; $data_array = array( ‘column_1′ => ‘new_data1′ ); $where_clause = array(
‘column_2′ => ‘data2′ ); $wpdb->update($table,$data_array,$where_clause);
To update data from the database There are many ways to get data, one of which is as follows:
$querystr = "SELECT column_1 FROM test_table"; $results = $wpdb->get_results($querystr); $i=0; while ($icolumn_1."<br>"; $i++; }
Query PHP syntax
<strong><?php $wpdb->query("DELETE FROM $wpdb->post WHERE post_id = ’13′ “); ?> </strong>
The parameter of query is any mysql statement. The return value is how many rows were selected and affected. Returns FALSE if an error occurs.
Select a variable
<strong><?php $wpdb->get_var('query',column_offset,row_offset); ?> </strong>
where query is the mysql statement to be queried. If it is empty, it means selecting it from the cache. column_Offset and row_offet indicate the column and row of the query return value, and the default value is zero. Typical usage is:
<?php $user_count = $wpdb->get_var($wpdb->prepare("SELECT COUNT(*) FROM $wpdb->users;"));?>
This SQL only selects one value. The default value is 0 rows and 0 columns, which means the number of users is selected. It's unclear why prepare is always added in front here.
Select a row
<strong><?php $wpdb->get_row('query', output_type, row_offset); ?> </strong>
query is the mysql statement to be executed, output_type indicates that the return value is object, hash or array; row_offset indicates the row.
By default, output_type is object.
$mylink = $wpdb->get_row("SELECT * FROM $wpdb->links WHERE link_id = 10");
echo $mylink->link_id; // prints "10"
if output_type=ARRAY_A , then:
$mylink = $wpdb->get_row("SELECT * FROM $wpdb->links WHERE link_id = 10", ARRAY_A); echo $mylink['link_id']; // prints "10"
Select a column
get_col('query',column_offset); ?>
Generally select
//$wpdb->get_results('query', output_type); <?php $fivesdrafts = $wpdb->get_results("SELECT ID, post_title FROM $wpdb->posts WHERE post_status = 'draft' AND post_author = 5"); foreach ($fivesdrafts as $fivesdraft) { echo $fivesdraft->post_title; }
Insert a row
<strong>//<?php $wpdb->insert( $table, $data, $format ); ?> <?php $wpdb->insert('table', array('column1' => 'value1', 'column2' => 123 ), array('%s','%d') ) ?></strong>
Update
//$wpdb->update( $table, $data, $where, $format = null, $where_format = null ); <?php $wpdb->update( 'table', array( 'column1' => 'value1', 'column2' => 'value2' ), array( 'ID' => 1 ), array( '%s', '%d' ), array( '%d' ) ) ?>
About wpdb prepare
As mentioned earlier, it is not clear why each mysql statement is included in prepare. Here is an explanation: Because the mysql statement may contain characters such as single quotes and double quotes, if it is not processed, it will be sent directly to mysql. , may cause errors. So here we use a prepare to preprocess the mysql statement. The syntax of prepare is:
$sql = $wpdb->prepare( 'query' [, value_parameter, value_parameter ... ] );
The query can contain %d, %S, and %f, which respectively indicate that the type of the following parameters is integer, character, and floating point. If you want to display the % sign, use %%. The syntax is basically the same as printf in C language.
That’s basically it. There should be no problem processing general databases. If you encounter problems, you can check it out in the article mentioned at the beginning of this article.
$wpdb is a global variable that contains multiple database query functions:
$wpdb -> get_results('query'); $wpdb->query('query'); $wpdb->get_var('query',column_offset,row_offset); $wpdb->get_row('query', output_type, row_offset); $wpdb->get_col('query',column_offset); $wpdb->get_results('query', output_type); $wpdb->insert( $table, $data, $format ); $wpdb->update( $table, $data, $where, $format = null, $where_format = null ); $wpdb->prepare( 'query' [, value_parameter, value_parameter ... ] ); $wpdb->show_errors(); $wpdb->hide_errors(); $wpdb->print_error(); $wpdb->get_col_info('type', offset); $wpdb->flush();
More: http://codex.wordpress.org/zh-cn:Class_Reference/wpdb
The above introduces the functions used in WordPress database operations. , including relevant content, I hope it will be helpful to friends who are interested in PHP tutorials.

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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