Bug #71410 COERCIBILITY(NULL) returns 6

• Submitted: 17 Jan 2014 16:44
• Modified: 18 Jan 2014 6:07
• Reporter: Federico Razzoli
• Status: Verified
• Category: MySQL Server: DML
• Severity: S3 (Non-critical)
• Version: 5.6, 5.6.15,5.5.35
• OS: Any
• CPU Architecture: Any

[17 Jan 2014 16:44] Federico Razzoli

Description:
This page:

http://dev.mysql.com/doc/refman/5.6/en/information-functions.html#function_coercibility

says that COERCIBILITY() returns 5 for:

"NULL or an expression derived from NULL"

This is true for expressions which return NULL, but if the value is exactly NULL, it returns 6 (which is not a documented value).

How to repeat:
SELECT COERCIBILITY(NULL), COERCIBILITY(NULL = 1);
+--------------------+------------------------+
| COERCIBILITY(NULL) | COERCIBILITY(NULL = 1) |
+--------------------+------------------------+
|                  6 |                      5 |
+--------------------+------------------------+
1 row in set (0.01 sec)

[17 Jan 2014 16:46] Federico Razzoli

fixed synopsis, was wrong

[18 Jan 2014 6:07] MySQL Verification Team

Hello Federico,

Thank you for the bug report.
Verified as described.

Thanks,
Umesh