Detailed introduction to the basics and processes of PHP and MySQL

PHP and MySQL are two tools commonly used in web development. Their main function is to process and manage databases when running web applications. This article will introduce the foundation and process of PHP and MySQL in detail.

1. Introduction to PHP

PHP (Hypertext Preprocessor) is an open source server-side scripting language that can be embedded in HTML and run on a Web server. PHP is an interpreted language that can dynamically generate HTML content at runtime. It can interact with the server and handle operations such as forms, file uploads, and databases. It can also generate dynamic content, control user access rights, etc.

2. Introduction to MySQL

MySQL is a relational database management system that supports running on a variety of operating systems. MySQL supports multi-user, multi-threading and other functions, and has good scalability, security and reliability. MySQL supports general SQL statements, transaction processing, stored procedures, triggers and other functions.

3. Combination of PHP and MySQL

PHP and MySQL can be used together easily. PHP provides some functions and class libraries that can be used to connect and operate MySQL database. PHP has a variety of APIs for communicating with MySQL. Using different APIs can achieve different effects. The most commonly used APIs are MySQLi and PDO.

4. Connecting to the MySQL database

Connecting to the MySQL database is the first step in using PHP to interact with MySQL. There are two functions for connecting to the database: mysqli_connect() and mysql_connect(). mysql_connect() has been deprecated and it is recommended to use mysqli_connect(). When connecting to the MySQL database, you need to specify the server address, user name, password, database name and other information. After the connection is successful, you can execute SQL statements, query data and other operations.

5. Execute SQL statements

When using MySQL in PHP, you need to use SQL statements to interact with the database. Usually the mysqli_query() function is used to execute SQL statements. This function returns a mysqli_result object, which can be used to read the returned data. Operations such as addition, deletion, modification, and query can be implemented using SQL statements.

6. Querying data

Querying data is a common operation. The SELECT statement is often used to query the data in the database, and the mysqli_fetch_array() function is used to read the query results. This function returns an array, and you can directly use the subscript to read the data of each row. You can also use the mysqli_fetch_assoc() function to obtain an associative array, using the column name as the key value of the array. The mysqli_fetch_row() function returns an index array whose index value corresponds to the column position.

7. Insert data

The SQL statement to insert data uses the INSERT INTO statement, which contains the table name and the value to be inserted. When inserting data, you need to use the mysqli_query() function to execute the SQL statement and check whether the execution result is successful. If the execution is successful, you can get the number of the last inserted data row through the mysqli_insert_id() function.

8. Modify and delete data

The SQL statements to modify and delete data are UPDATE and DELETE respectively. When performing a modification or deletion operation, you need to use the mysqli_query() function to execute the SQL statement and check whether the execution result is successful. If the execution is successful, it means that the data has been modified or deleted.

9. Close the connection

Close the connection is the last step in using PHP to interact with MySQL. You can use the mysqli_close() function to close the connection. Closing the connection frees up resources in the server and consumed memory. It is recommended to close the connection as soon as possible after completing the operation.

Summary

This article introduces the basic knowledge and processes of PHP and MySQL. PHP can be combined with MySQL to use SQL statements to operate the database. To connect to a MySQL database, you first need to connect to the database using the mysqli_connect() function. When executing SQL statements, you can use the mysqli_query() function. Query results can be read using the mysqli_fetch_array(), mysqli_fetch_assoc(), and mysqli_fetch_row() functions. The SQL statements for inserting, modifying, and deleting data are INSERT, UPDATE, and DELETE respectively, which can be executed through the mysqli_query() function. Finally, it is recommended to close the connection as soon as possible after the operation is completed.

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