-- { echoOn }

SELECT 'Union constants';
Union constants
SELECT 1 UNION ALL SELECT 1;
1
1
SELECT '--';
--
SELECT 1 UNION DISTINCT SELECT 1 UNION ALL SELECT 1;
1
1
SELECT '--';
--
SELECT 1 INTERSECT SELECT 1;
1
SELECT '--';
--
SELECT 1 EXCEPT SELECT 1;
SELECT '--';
--
SELECT id FROM (SELECT 1 AS id UNION ALL SELECT 1);
1
1
SELECT 'Union non constants';
Union non constants
SELECT value FROM (SELECT 1 as value UNION ALL SELECT 1 UNION ALL SELECT 1);
1
1
1
SELECT '--';
--
SELECT id FROM test_table UNION ALL SELECT id FROM test_table;
0
0
SELECT '--';
--
SELECT id FROM test_table UNION DISTINCT SELECT id FROM test_table;
0
SELECT '--';
--
SELECT id FROM test_table INTERSECT SELECT id FROM test_table;
0
SELECT '--';
--
SELECT id FROM test_table EXCEPT SELECT id FROM test_table;
SELECT '--';
--
SELECT id FROM (SELECT id FROM test_table UNION ALL SELECT id FROM test_table);
0
0
SELECT '--';
--
SELECT id FROM (SELECT id FROM test_table UNION DISTINCT SELECT id FROM test_table);
0
SELECT '--';
--
SELECT id FROM (SELECT id FROM test_table INTERSECT SELECT id FROM test_table);
0
SELECT '--';
--
SELECT id FROM (SELECT id FROM test_table EXCEPT SELECT id FROM test_table);