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src/test/regress/sql/select_having.sql
50 строк
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Tom Lane
Make the behavior of HAVING without GROUP BY conform to the SQL spec.
11 мар 2005, 02:21
11 мар 2005, 02:21
595ed2a
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-- -- 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; -- HAVING is effectively equivalent to WHERE in this case SELECT b, c FROM test_having GROUP BY b, c HAVING b = 3 ORDER BY b, c; SELECT lower(c), count(c) FROM test_having GROUP BY lower(c) HAVING count(*) > 2 OR min(a) = max(a) ORDER BY lower(c); SELECT c, max(a) FROM test_having GROUP BY c HAVING count(*) > 2 OR min(a) = max(a) ORDER BY c; -- test degenerate cases involving HAVING without GROUP BY -- Per SQL spec, these should generate 0 or 1 row, even without aggregates SELECT min(a), max(a) FROM test_having HAVING min(a) = max(a); SELECT min(a), max(a) FROM test_having HAVING min(a) < max(a); -- errors: ungrouped column references SELECT a FROM test_having HAVING min(a) < max(a); SELECT 1 AS one FROM test_having HAVING a > 1; -- the really degenerate case: need not scan table at all SELECT 1 AS one FROM test_having HAVING 1 > 2; SELECT 1 AS one FROM test_having HAVING 1 < 2; -- and just to prove that we aren't scanning the table: SELECT 1 AS one FROM test_having WHERE 1/a = 1 HAVING 1 < 2; DROP TABLE test_having;