94 lines
2.5 KiB
Plaintext
94 lines
2.5 KiB
Plaintext
--
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-- SELECT_HAVING
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--
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-- load test data
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CREATE TABLE test_having (a int, b int, c char(8), d char);
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INSERT INTO test_having VALUES (0, 1, 'XXXX', 'A');
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INSERT INTO test_having VALUES (1, 2, 'AAAA', 'b');
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INSERT INTO test_having VALUES (2, 2, 'AAAA', 'c');
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INSERT INTO test_having VALUES (3, 3, 'BBBB', 'D');
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INSERT INTO test_having VALUES (4, 3, 'BBBB', 'e');
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INSERT INTO test_having VALUES (5, 3, 'bbbb', 'F');
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INSERT INTO test_having VALUES (6, 4, 'cccc', 'g');
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INSERT INTO test_having VALUES (7, 4, 'cccc', 'h');
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INSERT INTO test_having VALUES (8, 4, 'CCCC', 'I');
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INSERT INTO test_having VALUES (9, 4, 'CCCC', 'j');
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SELECT b, c FROM test_having
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GROUP BY b, c HAVING count(*) = 1 ORDER BY b, c;
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b | c
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---+----------
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1 | XXXX
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3 | bbbb
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(2 rows)
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-- HAVING is effectively equivalent to WHERE in this case
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SELECT b, c FROM test_having
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GROUP BY b, c HAVING b = 3 ORDER BY b, c;
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b | c
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---+----------
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3 | bbbb
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3 | BBBB
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(2 rows)
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SELECT lower(c), count(c) FROM test_having
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GROUP BY lower(c) HAVING count(*) > 2 OR min(a) = max(a)
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ORDER BY lower(c);
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lower | count
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-------+-------
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bbbb | 3
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cccc | 4
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xxxx | 1
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(3 rows)
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SELECT c, max(a) FROM test_having
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GROUP BY c HAVING count(*) > 2 OR min(a) = max(a)
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ORDER BY c;
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c | max
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----------+-----
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bbbb | 5
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XXXX | 0
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(2 rows)
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-- test degenerate cases involving HAVING without GROUP BY
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-- Per SQL spec, these should generate 0 or 1 row, even without aggregates
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SELECT min(a), max(a) FROM test_having HAVING min(a) = max(a);
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min | max
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-----+-----
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(0 rows)
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SELECT min(a), max(a) FROM test_having HAVING min(a) < max(a);
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min | max
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-----+-----
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0 | 9
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(1 row)
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-- errors: ungrouped column references
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SELECT a FROM test_having HAVING min(a) < max(a);
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ERROR: column "test_having.a" must appear in the GROUP BY clause or be used in an aggregate function
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LINE 1: SELECT a FROM test_having HAVING min(a) < max(a);
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^
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SELECT 1 AS one FROM test_having HAVING a > 1;
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ERROR: column "test_having.a" must appear in the GROUP BY clause or be used in an aggregate function
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LINE 1: SELECT 1 AS one FROM test_having HAVING a > 1;
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^
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-- the really degenerate case: need not scan table at all
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SELECT 1 AS one FROM test_having HAVING 1 > 2;
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one
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-----
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(0 rows)
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SELECT 1 AS one FROM test_having HAVING 1 < 2;
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one
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-----
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1
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(1 row)
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-- and just to prove that we aren't scanning the table:
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SELECT 1 AS one FROM test_having WHERE 1/a = 1 HAVING 1 < 2;
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one
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-----
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1
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(1 row)
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DROP TABLE test_having;
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