select_having_1.out

PostgreSQL7.4.6 for Linux

--
-- SELECT_HAVING
--
-- load test data
CREATE TABLE test_having (a int, b int, c char(8), d char);
INSERT INTO test_having VALUES (0, 1, 'XXXX', 'A');
INSERT INTO test_having VALUES (1, 2, 'AAAA', 'b');
INSERT INTO test_having VALUES (2, 2, 'AAAA', 'c');
INSERT INTO test_having VALUES (3, 3, 'BBBB', 'D');
INSERT INTO test_having VALUES (4, 3, 'BBBB', 'e');
INSERT INTO test_having VALUES (5, 3, 'bbbb', 'F');
INSERT INTO test_having VALUES (6, 4, 'cccc', 'g');
INSERT INTO test_having VALUES (7, 4, 'cccc', 'h');
INSERT INTO test_having VALUES (8, 4, 'CCCC', 'I');
INSERT INTO test_having VALUES (9, 4, 'CCCC', 'j');
SELECT b, c FROM test_having
	GROUP BY b, c HAVING count(*) = 1 ORDER BY b, c;
 b |    c     
---+----------
 1 | XXXX    
 3 | bbbb    
(2 rows)

-- HAVING is equivalent to WHERE in this case
SELECT b, c FROM test_having
	GROUP BY b, c HAVING b = 3 ORDER BY b, c;
 b |    c     
---+----------
 3 | BBBB    
 3 | bbbb    
(2 rows)

SELECT lower(c), count(c) FROM test_having
	GROUP BY lower(c) HAVING count(*) > 2 OR min(a) = max(a)
	ORDER BY lower(c);
 lower | count 
-------+-------
 bbbb  |     3
 cccc  |     4
 xxxx  |     1
(3 rows)

SELECT c, max(a) FROM test_having
	GROUP BY c HAVING count(*) > 2 OR min(a) = max(a)
	ORDER BY c;
    c     | max 
----------+-----
 bbbb     |   5
 XXXX     |   0
(2 rows)

DROP TABLE test_having;