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join.result, select.result:

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Fixed bug #4976.
join_nested.result, join_nested.test:
  Added a test case for bug #4976.
sql_select.cc:
  Applied conversion from an outer join to an inner join 
  when the on expression does not depend on the outer table.
  It fixed bug #4976.
This commit is contained in:
igor@rurik.mysql.com
2004-08-10 17:32:15 -07:00
parent ff433d570b
commit 43bf2d055f
5 changed files with 46 additions and 7 deletions
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19
mysql-test/r/join_nested.result
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@ -1208,3 +1208,22 @@ SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.a=t3.a;
a a a
1 NULL NULL
DROP TABLE t1,t2,t3;
CREATE TABLE t1(a int, key (a));
CREATE TABLE t2(b int, key (b));
CREATE TABLE t3(c int, key (c));
INSERT INTO t1 VALUES (NULL), (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
(10), (11), (12), (13), (14), (15), (16), (17), (18), (19);
INSERT INTO t2 VALUES (NULL), (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
(10), (11), (12), (13), (14), (15), (16), (17), (18), (19);
INSERT INTO t3 VALUES (0), (1), (2), (3), (4), (5);
EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON c < 3 and b = c;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 index c c 5 NULL 6 Using where; Using index
1 SIMPLE t2 ref b b 5 test.t3.c 2 Using where; Using index
1 SIMPLE t1 index NULL a 5 NULL 21 Using index
EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range b b 5 NULL 3 Using where; Using index
1 SIMPLE t3 ref c c 5 test.t2.b 2 Using where; Using index
1 SIMPLE t1 index NULL a 5 NULL 21 Using index
DROP TABLE t1,t2,t3;