| Bug #8815 | Wrong string comparsion for cp1250_czech_cs collation | ||
|---|---|---|---|
| Submitted: | 25 Feb 2005 19:46 | Modified: | 8 Apr 2005 6:47 |
| Reporter: | Gleb Paharenko | Email Updates: | |
| Status: | No Feedback | Impact on me: | |
| Category: | MySQL Server | Severity: | S3 (Non-critical) |
| Version: | 4.1.10 | OS: | Linux (Linux) |
| Assigned to: | CPU Architecture: | Any | |
[26 Feb 2005 1:40]
MySQL Verification Team
Did you able for to run the second sample: create table tt(t1 varchar(5),t2 varchar(5)) default charset=cp1251 collate=cp1250_general_cs; I only find collate=cp1251_general_cs as valid one. Thank you in advance.
[26 Feb 2005 14:21]
Gleb Paharenko
Hi. I was unable to create such table because, really, there wasn't such collation cp1250_general_cs for character set cp1251(I think you wanted to write cp1250? ). I used cp1251 character set and cp1251_general_cs collation only as example for case sensitive collation. My idea was that empty string comparsion is wrong for cp1250_czech_cs, which is just national case sensitive czech collation. I think that comparsion of empty strings should be the same for all national collations, and really shouldn't depend on anything.
[26 Feb 2005 14:27]
Gleb Paharenko
I want to underline, that the problem is in cp1250_czech_cs collation. Empty string doesn't
equal to ''. See:
create table cz(a varchar(5)) default charset=cp1250 collate=cp1250_czech_cs;
mysql> insert into tz values('');
mysql> select a='' from cz;
+------+
| a='' |
+------+
| 0 |
+------+
We inserted '', but selecting a='' returns 0! (should return 1)
[7 Mar 2005 8:33]
Gleb Paharenko
Does the status change to Open After I'd added comments?
[7 Apr 2005 23:00]
Bugs System
No feedback was provided for this bug for over a month, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open".
[8 Apr 2005 6:47]
Gleb Paharenko
Wow! Why is it "No FeedBack"?
Description: Hello I think we have a wrong string comparsion in cp1250_czech_cs collation Because result is different from cp1251_general_cs, utf8_bin and other xxx_xxx_cs collations. It is just case sensitive, and the empty string shouldn't depend on country and all case sensitive collations should give the same results. How to repeat: mysql> create table ts(t1 varchar(5),t2 varchar(5)) default charset=cp1250 collate=cp1250_czech_cs; Query OK, 0 rows affected (0.06 sec) mysql> insert into ts values('a',''),('b',' '); Query OK, 2 rows affected (0.00 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select t2 ='' from ts; +--------+ | t2 ='' | +--------+ | 0 | | 0 | +--------+ And for other case sensivite collation it give another results mysql> create table tt(t1 varchar(5),t2 varchar(5)) default charset=cp1251 collate=cp1250_general_cs; mysql> insert into tt values('a',''),('b',' '); Query OK, 2 rows affected (0.00 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select t2 ='' from tt; +--------+ | t2 ='' | +--------+ | 1 | | 1 | +--------+ Suggested fix: Fix comparing of the empty strings.