In WordPress plug-in or theme development, the update() method of the wpdb class can be used to achieve database record updates. The basic structure is: $wpdb->update( $table, $data, $where, $format, $where_format). 1. $table specifies the table name, such as $wpdb->prefix . 'my_table'; 2. $data is an associative array, indicating the data to be updated, such as ['column1' => 'value1']; 3. $where is also an associative array, specifying the update conditions, such as ['id' => 123]; 4. $format and $where_format are optional, used to define data types, such as %s, %d, and %f. For example: Use $wpdb->update( $wpdb->prefix . 'users', ['user_email' => 'new@example.com'], ['ID' => 1], ['%s'], ['%d']) when updating the user's mailbox. Security needs to be noted: 1. Although update() is protected from SQL injection, complex queries should use $wpdb->prepare(); 2. Avoid manual stitching of SQL; 3. Verify and filter the input, such as intval() and sanitize_email(); 4. Use primary key or unique fields as WHERE conditions to prevent multiple records from being updated by mistake; 5. It is recommended to first SELECT query to confirm that the target exists. By mastering these methods and specifications, you can complete database update operations safely and efficiently.
Updating data is a common requirement in WordPress plug-in or theme development, and wpdb class is a key tool to achieve this goal. Use it to operate the database directly, but you should also pay attention to safety and specifications.
Basic usage: update method
wpdb provides a method specifically for updating records: update() . Its basic structure is as follows:
$wpdb->update( $table, $data, $where, $format = null, $where_format = null );
-
$table: The table name to be updated (such as$wpdb->prefix . 'my_table'). -
$data: The data to be updated in the format of an associative array (such as['column1' => 'value1', ...]). -
$where: Update condition, also associative array (such as['id' => 123]). -
$formatand$where_formatare optional parameters that specify the data type (%s string, %d integer, %f floating point number).
For example:
$wpdb->update(
$wpdb->prefix . 'users',
['user_email' => 'new@example.com'],
['ID' => 1],
['%s'],
['%d']
);Safety precautions
SQL injection is a potential risk when using wpdb to operate the database. Although the parameter binding process has been performed inside update() method, the following points need to be paid attention to:
- Always use
$wpdb->prepare()to construct complex query statements (althoughupdate()comes with a security mechanism, it may be required in other scenarios). - Avoid splicing of SQL statement strings directly.
- Verify and filter user input, such as using functions such as
intval(),sanitize_email(), etc.
For example, if you write a SQL update statement manually, it should be like this:
$wpdb->query(
$wpdb->prepare(
"UPDATE {$wpdb->prefix}users SET user_email = %s WHERE ID = %d",
'new@example.com',
1
)
);Use primary key or unique field as condition
When updating data, make sure your WHERE conditions are accurate enough, otherwise multiple records may be updated by mistake. The most common thing is to use primary keys (usually ID ) or unique fields (such as usernames, mailboxes, etc.) to locate the target row.
Suggested practices:
- Try to use integer primary keys as conditions.
- If you use the string field as a condition, remember to add the quote placeholder
%s. - Before updating, you can do a
SELECTquery to confirm whether the target exists.
Example:
$user_id = $wpdb->get_var(
$wpdb->prepare("SELECT ID FROM {$wpdb->prefix}users WHERE user_login = %s", 'admin')
);
if ($user_id) {
$wpdb->update(
$wpdb->prefix . 'users',
['user_email' => 'new@admin.com'],
['ID' => $user_id],
['%s'],
['%d']
);
} Basically that's it. By mastering the usage of wpdb::update() , combined with security measures and precise query conditions, you can steadily update database content in WordPress.
The above is the detailed content of How to update data using wpdb. For more information, please follow other related articles on the PHP Chinese website!
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