| Bug #30897 | GROUP_CONCAT returns extra comma on empty fields | ||
|---|---|---|---|
| Submitted: | 7 Sep 2007 14:36 | Modified: | 19 Nov 2007 4:56 |
| Reporter: | Philip Stoev | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server | Severity: | S3 (Non-critical) |
| Version: | 5.0.45-debug-log, 5.1 | OS: | Any |
| Assigned to: | Sergei Glukhov | CPU Architecture: | Any |
| Tags: | Contribution, qc | ||
[7 Sep 2007 19:18]
Hartmut Holzgraefe
mysqltest test case
Attachment: bug30897.tgz (application/x-gtar, text), 850 bytes.
[8 Sep 2007 17:09]
Martin Friebe
The issue seems to be caused by Item_func_group_concat::val_str in item_sum.cc. It checks if the result string has been written or not and write it if needed. It does so by checking the length of the result string: if (!result.length() && tree) In the case of yous an empty string in the result this is still 0, but no_appended is false. If the empty string is appended a 2nd time the separator is used. testing for no_appended (which will be False if anything, including the empty string is in result) seems the better option if (no_appended && tree)
[8 Sep 2007 17:09]
Martin Friebe
proposed patch
Attachment: bug30897.patch (text/x-patch), 413 bytes.
[25 Oct 2007 12:10]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/36339 ChangeSet@1.2537, 2007-10-25 17:05:53+05:00, gluh@mysql.com +3 -0 Bug#30897 GROUP_CONCAT returns extra comma on empty fields The fix is a copy of Martin Friebe's suggestion. added testing for no_appended which will be false if anything, including the empty string is in result
[29 Oct 2007 10:59]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/36538 ChangeSet@1.2555, 2007-10-29 14:53:10+04:00, gluh@mysql.com +3 -0 Bug#30897 GROUP_CONCAT returns extra comma on empty fields The fix is a copy of Martin Friebe's suggestion. added testing for no_appended which will be false if anything, including the empty string is in result
[16 Nov 2007 9:30]
Bugs System
Pushed into 5.0.52
[16 Nov 2007 9:33]
Bugs System
Pushed into 5.1.23-rc
[16 Nov 2007 9:35]
Bugs System
Pushed into 6.0.4-alpha
[19 Nov 2007 4:56]
Paul DuBois
Noted in 5.0.52, 5.1.23, 6.0.4 changelogs.
Description: GROUP_CONCAT returns a "," if the column in question contains only empty strings. It should return an empty string instead. How to repeat: mysql> create table t1 (f1 char(20)); Query OK, 0 rows affected (0.00 sec) mysql> insert into t1 values (''),(''); Query OK, 2 rows affected (0.00 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select group_concat(distinct f1) from t1; +---------------------------+ | group_concat(distinct f1) | +---------------------------+ | , | +---------------------------+ 1 row in set (0.00 sec) Suggested fix: It appears to me that there is some special handling in the code for empty strings, which does not work well