Char data type expression is not compatible with MYSQL 8.0

[dlyixue]

Bug Report

May I ask why the expression ' 'reports an error, however the expression ! ' ' is right ?
It is not compatible with MYSQL 8.0.
Thank for your reply.
Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

CREATE TABLE t0(c0 BLOB , c1 FLOAT UNIQUE );
INSERT INTO t0(c0, c1) VALUES ('abc', 0.123);
INSERT INTO t0(c0, c1) VALUES ('efg', 0.456);

UPDATE t0 SET c0='xyz' WHERE ' ';
UPDATE t0 SET c0='xyz' WHERE !' ';

2. What did you expect to see? (Required)

In MySQL

mysql> UPDATE t0 SET c0='xyz' WHERE ' ';
Query OK, 0 rows affected (0.01 sec)
Rows matched: 0  Changed: 0  Warnings: 0

mysql> UPDATE t0 SET c0='xyz' WHERE !' ';
Query OK, 2 rows affected, 1 warning (0.02 sec)
Rows matched: 2  Changed: 2  Warnings: 1

3. What did you see instead (Required)

mysql> UPDATE t0 SET c0='xyz' WHERE ' ';
ERROR 1292 (22007): Truncated incorrect DOUBLE value: ''
mysql> UPDATE t0 SET c0='xyz' WHERE !' ';
Query OK, 2 rows affected (0.01 sec)
Rows matched: 2  Changed: 2  Warnings: 0

4. What is your TiDB version? (Required)

Release Version: v8.1.0
Edition: Community
Git Commit Hash: 945d07c
Git Branch: HEAD
UTC Build Time: 2024-05-21 03:51:57
GoVersion: go1.21.10
Race Enabled: false
Check Table Before Drop: false
Store: tikv