How to optimize SQL in MySQL.

There are many methods for SQL optimization in MySQL, and here are some common ones:

1. Utilize indexes: Make sure that there are indexes on columns frequently queried in a table to speed up the queries. You can use the EXPLAIN statement to analyze the query execution plan and see if the indexes are being utilized.
2. Avoid using SELECT *: Only query the necessary columns, avoid querying all columns, which can save database resources and improve query performance.
3. Avoid using SELECT DISTINCT: if possible, try to avoid using the DISTINCT operator and use GROUP BY instead.
4. Choosing the appropriate data type can reduce storage space and improve query speed.
5. Avoid performing calculations on columns in the WHERE clause as it can prevent the database from using indexes.
6. Avoid using subqueries: Try to avoid using subqueries and opt for JOIN operations instead.
7. Regularly optimize table structure: Check table structure periodically to ensure it is efficient, and consider adding or removing indexes to improve query performance.
8. Avoid using temporary tables: Try to avoid using temporary tables by optimizing the query statements to decrease their use.
9. Process large amounts of data in batches: When dealing with a large amount of data, consider processing it in batches to prevent performance degradation caused by handling too much data at once.
10. Consider using caching to store query results and reduce the number of database queries.