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

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

Overview:

Database connection and query optimization are the basic principles of PHP underlying development vital part. Whether you are developing a small website or a large enterprise application, you need to interact with the database frequently. Therefore, understanding the main principles and practical skills of database connection and query optimization is very important to improve the performance and stability of applications.

1. Database connection principle

Before connecting to the database, we first need to configure the database connection information. Normally, we define parameters such as the database server address, database user name, password, and database name in the application configuration file.

When the application needs to interact with the database, it will first use the corresponding database extension library (such as mysqli, PDO, etc.) to establish a connection with the database server. Connection is achieved by using network protocols such as TCP/IP to communicate between the application and the database server. When connecting, you need to pass necessary parameters such as server address, user name, password, etc. After the database server receives the connection request, it will perform identity verification and establish the connection after passing the verification.

After the connection is successful, the application can interact with the database through the relevant functions or methods provided by the database extension library. You can perform operations such as querying, updating data, and executing stored procedures.

When making database connections, you need to pay attention to the following aspects:

1. Connection pool management: In order to improve the efficiency and performance of the connection, you can use the connection pool to manage the connection. The connection pool will pre-establish a certain number of connections and save them in a connection pool. When an application needs a connection, it can obtain an available connection from the connection pool and return it to the connection pool after use. This can reduce the overhead of frequently creating and closing connections, and improve connection reuse and response speed.
2. Long connection and short connection: A long connection means that after the application establishes a connection with the database server, it remains connected and does not close the connection. A short connection means that the connection will be closed after each operation is completed. Long connections can reduce the cost of establishing and closing connections, and are suitable for scenarios where database operations are frequent. However, it should be noted that long connections may cause a waste of connection resources, so the connection life cycle needs to be configured appropriately.
3. Error handling and exception handling: When making database connections, error and exception handling should be considered. The connection may not be established due to network problems or other reasons. In this case, error handling should be performed and corresponding error information should be returned. Some common database errors can be captured and handled through exception handling. Proper error and exception handling can improve the robustness and maintainability of your code.

2. Practical skills for query optimization

Database query is one of the common operations in applications, so optimizing query performance is an important part of improving application performance. Listed below are some common query optimization practical techniques.

1. Use appropriate indexes: Indexes are an important means to improve query performance. When designing database tables, appropriate indexes should be created based on query needs. Indexes can speed up queries and reduce the number of database scans. But too many or unnecessary indexes will increase the cost of write operations, so there is a trade-off.
2. Avoid full table scan: Full table scan refers to scanning the entire table. Such query efficiency is usually very low. You can avoid full table scans by adding indexes, optimizing query conditions, and using JOIN.
3. Use the appropriate connection method: When performing multi-table queries, you should choose the appropriate connection method. If the query result requires only some fields, you can query only the required fields to avoid the transmission and processing of useless data. At the same time, you should pay attention to whether to use inner or outer connections. Inner connections are usually more efficient.
4. Paging query optimization: For situations where paging query is required, the query conditions and LIMIT statement should be optimized. The efficiency of paging queries can be improved through reasonable indexing, modifying query conditions, and adjusting LIMIT statements.
5. Precompiling and binding parameters: Precompiling and binding parameters is one of the important means to improve query performance and security. Precompilation can reduce the parsing overhead of SQL statements and improve execution efficiency. Binding parameters can effectively prevent SQL injection attacks.

Summary:

Database connection and query optimization are important links that cannot be ignored in the underlying development of PHP. Understanding the principles and practical techniques of database connections can improve the performance and stability of your applications. At the same time, query performance can be effectively optimized by properly configuring the connection pool, selecting appropriate connection methods, using appropriate indexes, and writing optimized query statements. Database connections and query optimization are important skills that every PHP developer should master.

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