How do you approach solving an SQL problem?

The approach to solving an SQL problem typically includes the following steps:

1. Understanding the problem — clearly define what information needs to be obtained or what operation to perform.
2. Analyzing data structure — study the tables, their relationships, data types, and constraints.
3. Determining necessary tables and fields — select data sources for the query.
4. Constructing the query — start with a simple SELECT, gradually adding JOIN, WHERE, GROUP BY, HAVING, and other clauses.
5. Using subqueries — for complex conditions or aggregation, when intermediate results are needed.
6. Optimization — check the execution plan, add indexes if necessary.

Example: get a list of customers whose total orders exceed 1000.

SELECT customer_id, SUM(order_amount) AS total
FROM orders
GROUP BY customer_id
HAVING SUM(order_amount) > 1000;

If the task is more complex, subqueries can be used:

SELECT c.customer_id, c.name
FROM customers c
WHERE c.customer_id IN (
  SELECT customer_id
  FROM orders
  GROUP BY customer_id
  HAVING SUM(order_amount) > 1000
);

This approach helps break down the task into parts and build the solution step by step.