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1. Index optimization: Make sure that you have appropriate indexes on the fields used in your query. Indexes can significantly speed up data retrieval, but be careful not to over-index, because while indexes speed up queries, they slow down table updates.

2. Query statement optimization: Avoid using SELECT * and try to specify the required columns. This will reduce the amount of data transferred and improve query efficiency.

3. Use the appropriate JOIN type：Choose appropriate JOIN operations according to actual conditions, such as INNER JOIN, LEFT JOIN, etc., and avoid using resource-consuming CROSS JOIN.

4. WHERE clause optimization: Use columns that can be quickly searched in the WHERE clause and avoid using functions or expressions because this will cause indexes to fail.

5. Aggregate functions and GROUP BY optimization: When performing aggregation operations, make sure that the columns in the GROUP BY clause are indexed and only aggregate the necessary columns.

6. LIMIT Clause Usage: If you only need the first few rows of the query result, use the LIMIT clause to reduce the amount of data queried.

7. Subquery and temporary table optimization：Sometimes rewriting a subquery into a join query (JOIN) can improve efficiency. At the same time, avoid using too many temporary tables in the query.

8. Using the query cache: If the database supports it, you can use the query cache to store repeated query results and reduce the computational burden of the database.

9. Database Normalization: Design the database table structure reasonably to avoid data redundancy, but also pay attention to excessive JOIN operations that may result from over-normalization.

10. Hardware and configuration optimization: Upgrading hardware, such as a faster CPU, more RAM, or faster storage devices, and optimizing database configuration, such as adjusting buffer sizes, can increase query speed.

11. Analyze and explain execution plans: Use EXPLAIN or similar tools to analyze the query execution plan, identify performance bottlenecks and optimize them.

12. Regular maintenance: Perform regular database maintenance, such as updating statistics, rebuilding indexes, cleaning up fragments, etc., to maintain database performance.