How to modify data in database using PHP

PHP is a server-side scripting language that is popular for website development and dynamic web page generation. In PHP, modifying data is a very important operation. This article will introduce how to use PHP to modify data.

1. Connect to the database

Use the mysql_connect() function in PHP to connect to the database. This function requires a connection based on parameters such as the IP address, username, and password of the database server. After the connection is successful, use the mysql_select_db() function to select the database.

2. Query data

Use the mysql_query() function to query data in the database. This function requires passing in SQL statements as parameters. The query results are stored in a resource variable, and the data can be fetched row by row using the mysql_fetch_array() function.

3. Modify data

Use the UPDATE statement to modify the data in the database. The UPDATE statement needs to specify the table name, data to be modified, and conditions. For example, to change the username field of the record with id 1 in the table to "John", you can use the following code:

$sql = "UPDATE users SET username='John' WHERE id=1";
mysql_query($sql);

4. Delete data

Use the DELETE statement to delete data in the database. The DELETE statement requires specifying the table name and conditions. For example, to delete the record with id 1 in the table, you can use the following code:

$sql = "DELETE FROM users WHERE id=1";
mysql_query($sql);

5. Close the database connection

After use, you need to use the mysql_close() function Close the database connection.

Summary:

Through the above steps, you can use PHP to modify the data in the database. However, there are data security issues that need to be taken into consideration. In order to avoid problems such as SQL injection attacks, security measures such as using prepared statements or escaping special characters need to be used.

At the same time, in order to improve the readability and maintainability of the code, it is recommended to encapsulate database operations as functions or classes and use object-oriented programming ideas for development to improve the reusability of the code.

In actual development, you can also use tools such as ORM framework to simplify database operations and improve development efficiency.

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