Bug #79656 "'2' + 0.0, group_concat('2') + 0.0" are returning different result

• Submitted: 16 Dec 2015 4:00
• Modified: 16 Dec 2015 7:48
• Reporter: Su Dylan
• Status: Verified
• Category: MySQL Server: DML
• Severity: S3 (Non-critical)
• Version: 5.7.8, 5.5.48, 5.6.28, 5.7.10
• OS: Any
• CPU Architecture: Any

[16 Dec 2015 4:00] Su Dylan

Description:
Output:
=======
mysql> select '2' + 0.0, group_concat('2') + 0.0, cast(group_concat('2') as char) + 0.0;
+-----------+-------------------------+---------------------------------------+
| '2' + 0.0 | group_concat('2') + 0.0 | cast(group_concat('2') as char) + 0.0 |
+-----------+-------------------------+---------------------------------------+
|         2 |                     2.0 |                                     2 |
+-----------+-------------------------+---------------------------------------+
1 row in set (0.00 sec)

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.8-rc  |
+-----------+
1 row in set (0.00 sec)

Problem:
========
'2' + 0.0, group_concat('2') + 0.0 should return consistent result, 2 expected here.

How to repeat:
select '2' + 0.0, group_concat('2') + 0.0, cast(group_concat('2') as char) + 0.0;

Suggested fix:
'2' + 0.0, group_concat('2') + 0.0 should return consistent result, 2.

[16 Dec 2015 7:48] MySQL Verification Team

Hello Su Dylan,

Thank you for the report.

Thanks,
Umesh