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Bug #54190: Comparison to row subquery produces incorrect

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result

Row subqueries producing no rows were not handled as UNKNOWN
values in row comparison expressions.

That was a result of the following two problems:

1. Item_singlerow_subselect did not mark the resulting row
value as NULL/UNKNOWN when no rows were produced.

2. Arg_comparator::compare_row() did not take into account that
a whole argument may be NULL rather than just individual scalar
values.

Before bug#34384 was fixed, the above problems were hidden
because an uninitialized (i.e. without any stored value) cached
object would appear as NULL for scalar values in a row subquery
returning an empty result. After the fix
Arg_comparator::compare_row() would try to evaluate
uninitialized cached objects.

Fixed by removing the aforementioned problems.


mysql-test/r/row.result:
  Added a test case for bug #54190.
mysql-test/r/subselect.result:
  Updated the result for a test relying on wrong behavior.
mysql-test/t/row.test:
  Added a test case for bug #54190.
sql/item_cmpfunc.cc:
  If either of the argument rows is NULL, return NULL as the
  result of comparison.
sql/item_subselect.cc:
  Adjust null_value for Item_singlerow_subselect depending on
  whether a row has been produced by the row subquery.
This commit is contained in:
Alexey Kopytov
2010-09-09 16:46:13 +04:00
parent 8822ecff2d
commit 453107bc56
5 changed files with 55 additions and 3 deletions
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19
mysql-test/t/row.test
View File

@@ -266,3 +266,22 @@ SELECT 1 FROM t1 WHERE ROW(a, b) >=
ROW('1', (SELECT 1 FROM t1 WHERE a > 1234));
--enable_warnings
DROP TABLE t1;
--echo #
--echo # Bug #54190: Comparison to row subquery produces incorrect result
--echo #
SELECT ROW(1,2) = (SELECT 1,2 FROM DUAL WHERE 1 = 0);
SELECT ROW(1,2) = (SELECT 1,3 FROM DUAL WHERE 1 = 0);
CREATE TABLE t1 (i INT);
INSERT INTO t1 () VALUES (1), (2), (3);
SELECT ROW(1,2) = (SELECT 1,2 FROM t1 WHERE 1 = 0);
SELECT ROW(1,2) = (SELECT 1,3 FROM t1 WHERE 1 = 0);
SELECT i FROM t1 WHERE ROW(1,2) = (SELECT 1,2 FROM DUAL WHERE 1 = 0);
SELECT i FROM t1 WHERE ROW(1,2) = (SELECT 1,3 FROM DUAL WHERE 1 = 0);
DROP TABLE t1;
--echo End of 5.1 tests