How to execute complex subqueries in SQLite?

To execute complex subqueries in SQLite, you can use either nested subqueries or use the WITH clause for recursive queries. Here are examples of both methods:

  1. Utilizing nested subqueries:
SELECT column1, column2
FROM table1
WHERE column1 IN (SELECT column1 FROM table2 WHERE column2 = 'value');

In this example, the inner subquery is executed first and returns the results that meet the criteria, which are then further filtered and processed by the outer query.

  1. Performing a recursive query using a WITH clause:
WITH recursive cte AS (
  SELECT column1, column2
  FROM table1
  WHERE column1 = 'value'
  SELECT column1, column2
  FROM table2
  WHERE column2 IN (SELECT column1 FROM cte)
FROM cte;

In this example, a recursive common table expression (CTE) is created using a WITH clause, where multiple SELECT statements are defined and connected together using UNION ALL. Finally, this CTE is referenced in the outer query to retrieve the final result.

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