Bug #120523 Wrong result for arithmetic expression involving DAYNAME() and BIT column

• Submitted: 22 May 9:13
• Modified: 25 May 20:10
• Reporter: ss w
• Status: Verified
• Category: MySQL Server: Optimizer
• Severity: S3 (Non-critical)
• Version: 8.0.43
• OS: Any
• CPU Architecture: Any

[22 May 9:13] ss w

Description:
A query using an arithmetic expression involving DAYNAME() and a BIT column may evaluate inconsistently between WHERE filtering and direct SELECT expression evaluation.

In this case, the expression multiplies the string result returned by DAYNAME() with a BIT value. The WHERE query correctly evaluates the expression as FALSE and returns an empty result set, while direct SELECT expression evaluation incorrectly treats the same expression as TRUE.

How to repeat:
CREATE TABLE t1611 (c1 BIT);
INSERT INTO t1611 (c1) VALUES (b'1');
SELECT t1611.c1 FROM t1611 WHERE (DAYNAME('2005-11-19 12:30:27') * t1611.c1);
-- return 0 rows
SELECT SUM(count) FROM (SELECT (DAYNAME('2005-11-19 12:30:27') * t1611.c1) IS TRUE AS count FROM t1611) AS ta_norec;
-- return 1

[25 May 20:10] Roy Lyseng

Thank you for the bug report.
Verified as described.