Bug #77376 " ('xxx' <=> null) is not known " returns 0
Submitted: 17 Jun 2015 2:38 Modified: 17 Jun 2015 7:47
Reporter: Su Dylan Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: DML Severity:S3 (Non-critical)
Version:5.6.22, 5.6.25 OS:Any
Assigned to: CPU Architecture:Any

[17 Jun 2015 2:38] Su Dylan
Description:
mysql> select '6' <=> null, ('6' <=> null) is not unknown, 0 is not unknown, version();
+--------------+-------------------------------+------------------+------------+
| '6' <=> null | ('6' <=> null) is not unknown | 0 is not unknown | version()  |
+--------------+-------------------------------+------------------+------------+
|            0 |                             0 |                1 | 5.6.22-log |
+--------------+-------------------------------+------------------+------------+

How to repeat:
select '6' <=> null, ('6' <=> null) is not unknown, 0 is not unknown, version();

Suggested fix:
('6' <=> null) is not unknown should return 1.
[17 Jun 2015 6:23] MySQL Verification Team
Hello Su,

Thanks for the report.

Thanks,
Umesh
[17 Jun 2015 7:47] Su Dylan
Another expr with null returns 0/1:

mysql> select a,b,(b between null and null),version() from t1;
+---+------------+---------------------------+------------+
| a | b          | (b between null and null) | version()  |
+---+------------+---------------------------+------------+
| 1 | 2015-01-01 |                         0 | 5.6.22-log |
| 2 | NULL       |                      NULL | 5.6.22-log |
+---+------------+---------------------------+------------+
2 rows in set (0.00 sec)