Detailed explanation of PHP underlying development principles: practical skills in database connection and query optimization

Detailed explanation of PHP underlying development principles: practical skills for database connection and query optimization

Overview:
Database is one of the most commonly used components in web applications. For PHP applications, the efficiency of database connections and queries is crucial to the performance of the entire application. This article will delve into the underlying development principles of PHP, focus on practical tips for optimizing database connections and queries, and provide some code examples.

1. Database connection optimization:
   Database connection is one of the essential steps for every PHP application. When making database connections, we should try to avoid too many connection operations to reduce the burden on the database server. The following are some practical tips for database connection optimization:

1.1 Use persistent connections:
Using persistent connections can reduce the connection overhead for each request. When connecting to the database, use the mysqli_pconnect() function instead of the mysqli_connect() function to enable a persistent connection.

Sample code:

$mysqli = mysqli_pconnect('localhost', 'username', 'password', 'database');

1.2 Optimizing connection parameters:
By optimizing connection parameters, the performance of database connections can be improved. For example, adjust the max_connections parameter to adapt to the number of concurrent connections, increase the wait_timeout parameter to avoid connection timeouts, etc.

Sample code:

$mysqli = new mysqli('localhost', 'username', 'password', 'database');
$mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 2); // 设置连接超时时间为2秒
$mysqli->options(MYSQLI_OPT_READ_TIMEOUT, 5); // 设置读取超时时间为5秒

2. Query optimization:
   Database query is one of the most commonly performed operations in an application, so optimizing the query can significantly improve the performance of the application. The following are some common query optimization practical skills:

2.1 Using indexes:
Indexes are an important tool for accelerating database queries. When designing database tables, properly defining indexes can greatly improve query efficiency. Common index types include primary key index, unique index, ordinary index, etc.

Sample code:

CREATE TABLE `users` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(50) NOT NULL,
  `email` VARCHAR(100) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `email` (`email`)
) ENGINE=InnoDB;

2.2 Prepared statements:
Prepared statements can reduce the risk of SQL injection and improve query performance. Through prepared statements, we can template SQL statements and bind parameter values ​​during execution.

Sample code:

$stmt = $mysqli->prepare("SELECT * FROM users WHERE age > ?");
$stmt->bind_param("i", $age);
$age = 18;
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
    echo $row['name'];
}
$stmt->close();

2.3 Use appropriate query statements:
When writing query statements, you should choose appropriate query statements based on actual needs. For example, using SELECT * will return all column information, which may cause unnecessary data transmission and should be avoided as much as possible.

Sample code:

$query = "SELECT name, email FROM users WHERE age > 18";
$result = $mysqli->query($query);
while ($row = $result->fetch_assoc()) {
    echo $row['name'];
}
$result->close();

Conclusion:
Through the detailed explanation of the underlying development principles of PHP, we understand the practical skills of database connection and query optimization. Properly optimizing database connections and queries can significantly improve the performance of PHP applications, thereby providing a better user experience. I hope that the explanation in this article can help readers understand and apply the underlying development principles of PHP more deeply.

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