Bugs item #1960253, was opened at 2008-05-08 15:17
Message generated for change (Comment added) made by romulog
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Category: SQL/Core
Group: SQL CVS Head
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Romulo Goncalves (romulog)
Assigned to: Niels Nes (nielsnes)
Summary: comparison with several values
Initial Comment:
The example shows the problem:
sql>select * from tables where id = 0 = 1 = 0 = 1 LIMIT 1;
+-----+--------+----------+------+-----+-------+--------------+----------+
| id |name |schema_id |query |type |system |commit_action |temporary |
+=====+========+==========+======+=====+=======+==============+==========+
| 980 |schemas | 979 |null | 0 |true | 0 | 0 |
+-----+--------+----------+------+-----+-------+--------------+----------+
sql>
The problem is in the this part of the sql_parser:
predicate:
comparison_predicate
| between_predicate
| like_predicate
| test_for_null
| in_predicate
| all_or_any_predicate
| existence_test
| scalar_exp
;
pred_exp:
predicate
;
To compare we have the following cases:
comparison_predicate:
pred_exp COMPARISON pred_exp
| pred_exp '=' pred_exp
;
It not only allows infinite comparison using pred_exp, but it also has wrong
semantics once the comparison is done to more than one value.
----------------------------------------------------------------------
>Comment By: Romulo Goncalves (romulog)
Date: 2008-05-08 15:24
Message:
Logged In: YES
user_id=1498628
Originator: YES
Well,
The semantics might be correct because there is no table with id = 0 (id =
0 false), but if then I do "= 1 = 0 = 1" I make the clause id = 0 (which
was false) true.
In this case I will get the first row of the table tables (because I used
LIMIT 1).
Is this correct and accepted on SQL?
Romulo
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