1--
2-- SELECT_HAVING
3--
4-- load test data
5CREATE TABLE test_having (a int, b int, c char(8), d char);
6INSERT INTO test_having VALUES (0, 1, 'XXXX', 'A');
7INSERT INTO test_having VALUES (1, 2, 'AAAA', 'b');
8INSERT INTO test_having VALUES (2, 2, 'AAAA', 'c');
9INSERT INTO test_having VALUES (3, 3, 'BBBB', 'D');
10INSERT INTO test_having VALUES (4, 3, 'BBBB', 'e');
11INSERT INTO test_having VALUES (5, 3, 'bbbb', 'F');
12INSERT INTO test_having VALUES (6, 4, 'cccc', 'g');
13INSERT INTO test_having VALUES (7, 4, 'cccc', 'h');
14INSERT INTO test_having VALUES (8, 4, 'CCCC', 'I');
15INSERT INTO test_having VALUES (9, 4, 'CCCC', 'j');
16SELECT b, c FROM test_having
17	GROUP BY b, c HAVING count(*) = 1 ORDER BY b, c;
18 b |    c
19---+----------
20 1 | XXXX
21 3 | bbbb
22(2 rows)
23
24-- HAVING is effectively equivalent to WHERE in this case
25SELECT b, c FROM test_having
26	GROUP BY b, c HAVING b = 3 ORDER BY b, c;
27 b |    c
28---+----------
29 3 | BBBB
30 3 | bbbb
31(2 rows)
32
33SELECT lower(c), count(c) FROM test_having
34	GROUP BY lower(c) HAVING count(*) > 2 OR min(a) = max(a)
35	ORDER BY lower(c);
36 lower | count
37-------+-------
38 bbbb  |     3
39 cccc  |     4
40 xxxx  |     1
41(3 rows)
42
43SELECT c, max(a) FROM test_having
44	GROUP BY c HAVING count(*) > 2 OR min(a) = max(a)
45	ORDER BY c;
46    c     | max
47----------+-----
48 bbbb     |   5
49 XXXX     |   0
50(2 rows)
51
52-- test degenerate cases involving HAVING without GROUP BY
53-- Per SQL spec, these should generate 0 or 1 row, even without aggregates
54SELECT min(a), max(a) FROM test_having HAVING min(a) = max(a);
55 min | max
56-----+-----
57(0 rows)
58
59SELECT min(a), max(a) FROM test_having HAVING min(a) < max(a);
60 min | max
61-----+-----
62   0 |   9
63(1 row)
64
65-- errors: ungrouped column references
66SELECT a FROM test_having HAVING min(a) < max(a);
67ERROR:  column "test_having.a" must appear in the GROUP BY clause or be used in an aggregate function
68LINE 1: SELECT a FROM test_having HAVING min(a) < max(a);
69               ^
70SELECT 1 AS one FROM test_having HAVING a > 1;
71ERROR:  column "test_having.a" must appear in the GROUP BY clause or be used in an aggregate function
72LINE 1: SELECT 1 AS one FROM test_having HAVING a > 1;
73                                                ^
74-- the really degenerate case: need not scan table at all
75SELECT 1 AS one FROM test_having HAVING 1 > 2;
76 one
77-----
78(0 rows)
79
80SELECT 1 AS one FROM test_having HAVING 1 < 2;
81 one
82-----
83   1
84(1 row)
85
86-- and just to prove that we aren't scanning the table:
87SELECT 1 AS one FROM test_having WHERE 1/a = 1 HAVING 1 < 2;
88 one
89-----
90   1
91(1 row)
92
93DROP TABLE test_having;
94