Can you explain what SQL query optimization is and how it is achieved?

SQL query optimization is the process of improving the performance of a database query to reduce its execution time and system load. This is achieved by selecting efficient execution plans, minimizing read and write operations, and properly utilizing indexes.

Main optimization methods:

• Using indexes to speed up data retrieval.
• Avoiding redundant or complex JOINs.
• Limiting the selection to only necessary columns and rows (SELECT with WHERE).
• Analyzing the query execution plan (EXPLAIN) to identify bottlenecks.
• Caching frequently used data.

Example: if you have a users table and often search by email, it is advisable to create an index on this field to make queries faster.