How to optimize SQL query performance?

To improve the efficiency of SQL queries, you can consider the following aspects:

1. Utilize proper indexes: Make sure that all columns involved in a query have the appropriate indexes in place to reduce the database’s scanning time. You can use the EXPLAIN statement to view the query’s execution plan and check if any indexes are being utilized.
2. Optimize your query: try to avoid wildcard searches, unnecessary JOIN operations, and use the WHERE clause to limit the data range as much as possible.
3. Prefer using INNER JOIN and other types of join queries over subqueries when performing connections to avoid querying the database multiple times.
4. Avoid sorting and grouping large amounts of data: try to minimize the use of ORDER BY and GROUP BY in queries, as sorting and grouping can be done within the application.
5. Choose the appropriate storage engine, such as InnoDB or MyISAM, based on your needs to improve query performance.
6. Utilize caching: Caching can be used to store query results, reducing the number of times the database is accessed.
7. Regularly optimize the database by removing unused indexes, rebuilding indexes, and optimizing table structures.

The efficiency of SQL queries can be improved using these methods, speeding up the retrieval of data.