How to optimize database queries in PHP backend function development?

How to optimize database queries in PHP backend function development?

When developing PHP back-end functions, database query is a common and critical link. Optimizing database queries can improve system performance and responsiveness, thereby providing a better user experience. This article will introduce how to optimize database queries in PHP back-end function development from different angles, and provide corresponding code examples.

1. Use indexes
   Indexes are the key to improving database query efficiency. When designing the database, select appropriate fields to create indexes based on the frequency of queries and field selectivity, and ensure that the value type of the field matches the index type. The following is a sample code:

// 创建索引
CREATE INDEX idx_name ON table_name (column_name);

// 查询时使用索引
SELECT * FROM table_name WHERE column_name = value;

2. Use the appropriate query statement
   Select the appropriate query statement based on the data you need to query. Use LIMIT to limit the number of records returned to avoid returning large amounts of data. The following is a sample code:

// 查询前10条记录
SELECT * FROM table_name LIMIT 10;

// 查询名字以'A'开头的记录
SELECT * FROM table_name WHERE name LIKE 'A%';

3. Database connection reuse
   In PHP, database connections are expensive operations, and the creation and destruction of connections can be reduced through connection reuse. . The following is a sample code:

// 连接数据库
$connection = mysqli_connect('localhost', 'username', 'password', 'database');

// 复用连接进行多次查询
$query1 = mysqli_query($connection, 'SELECT * FROM table_name');
$query2 = mysqli_query($connection, 'SELECT * FROM table_name');

4. Batch query and batch insert
   Through batch query and batch insert operations, you can reduce the number of interactions with the database and improve efficiency. The following is a sample code:

// 批量查询
SELECT * FROM table_name WHERE id IN (1, 2, 3, 4, 5);

// 批量插入
INSERT INTO table_name (column1, column2) VALUES (value1, value2), (value3, value4), (value5, value6);

5. Avoid using wildcard queries
   Wildcard queries (such as �c%) will cause a full table scan and affect performance. Try to avoid using wildcard queries unless necessary. The following is a sample code:

// 避免使用通配符查询
SELECT * FROM table_name WHERE name LIKE '%abc%';

6. Caching query results
   For some relatively stable query results, caching can be used to reduce database queries. You can use caching tools such as Redis and Memcached. The following is a sample code:

// 查询结果缓存一小时
$redis = new Redis();
$redis->connect('localhost');
$cacheKey = 'query_result_key';

if ($redis->exists($cacheKey)) {
    // 从缓存中获取结果
    $result = $redis->get($cacheKey);
} else {
    // 从数据库查询结果
    $result = mysqli_query($connection, 'SELECT * FROM table_name');

    // 将结果存入缓存
    $redis->setex($cacheKey, 3600, $result);
}

PHP can be significantly improved by using indexes, choosing appropriate query statements, reusing database connections, batching queries and inserts, avoiding wildcard queries, and caching query results. Database query performance in backend feature development. In actual development, appropriate optimization solutions can be selected according to specific circumstances, and necessary performance testing and tuning can be performed.

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