避免重复引用多个连接表的子查询

SELECT DISTINCT t1.column1, t2.column2
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
JOIN table3 t3 ON t2.id = t3.id

SELECT t1.column1, t2.column2
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
JOIN table3 t3 ON t2.id = t3.id
GROUP BY t1.column1, t2.column2

SELECT t1.column1, t2.column2
FROM (
  SELECT column1, id
  FROM table1
) t1
JOIN (
  SELECT column2, id
  FROM table2
) t2 ON t1.id = t2.id
JOIN (
  SELECT column3, id
  FROM table3
) t3 ON t2.id = t3.id

SELECT DISTINCT t1.column1, t2.column2, t3.column3,
       ROW_NUMBER() OVER (PARTITION BY t1.column1, t2.column2 ORDER BY t3.column3) AS row_num
FROM table1 t1
JOIN table2 t2 ON t1.id = t2.id
JOIN table3 t3 ON t2.id = t3.id
WHERE row_num = 1