WITH result1(amount, src__id, period) AS (VALUES (76000, '006anGu2H5ygdjh5cK', 'FY2023-Q2'),
(353000, '006bkoWWx3f7XK4kre', 'FY2023-Q3')),
result2(amount, src__id, period) AS (VALUES (353000, '006bkoWWx3f7XK4kre', 'FY2023-Q2'),
(320000, '006EAvTFuCNbXs8vfV', 'FY2023-Q2')),
result3(amount, src__id, period) AS (VALUES (353000, '006bkoWWx3f7XK4kre', 'FY2023-Q3'),
(320000, '006EAvTFuCNbXs8vfV', 'FY2023-Q2'))
SELECT COALESCE(r1.amount, 0) AS amount1,
COALESCE(r2.amount, 0) AS amount2,
COALESCE(r3.amount, 0) AS amount3,
COALESCE(r1.src__id, COALESCE(r2.src__id, r3.src__id)) AS src__id,
COALESCE(r1.period, COALESCE(r2.period, r3.period)) AS period,
0 AS placeholder_column
FROM result1 r1
full join result2 r2 using (src__id,period)
full join result3 r3 using (src__id,period)
-- LEFT JOIN result2 r2 ON r1.src__id = r2.src__id AND r1.period = r2.period
-- LEFT JOIN result3 r3 ON r1.src__id = r3.src__id AND r1.period = r3.period