Вот несколько способов достижения функциональности DISTINCT в SQL:

1. Использование ключевого слова DISTINCT:

   SELECT DISTINCT column_name FROM table_name;

2. Использование GROUP BY:

   SELECT column_name FROM table_name GROUP BY column_name;

3. Использование подзапроса:

   SELECT column_name
   FROM (SELECT column_name FROM table_name) AS subquery

4. Использование функции ROW_NUMBER():

   SELECT column_name
   FROM (
      SELECT column_name, ROW_NUMBER() OVER (PARTITION BY column_name ORDER BY column_name) AS rn
      FROM table_name
   ) AS subquery
   WHERE rn = 1;

5. Использование ключевого слова EXISTS:

   SELECT t1.column_name
   FROM table_name t1
   WHERE NOT EXISTS (
      SELECT 1
      FROM table_name t2
      WHERE t2.column_name = t1.column_name
          AND t2.primary_key < t1.primary_key
   );