can insert null value into not null column

[yiduoyunQ]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

set session sql_mode = '';
create table a (id int primary key,b  varchar(10) not null default '');
insert into a values(4, null);

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

mysql> insert into a values(4, null);
ERROR 1146 (42S02): Table 'test.a' doesn't exist

3. What did you see instead (Required)

mysql> set session sql_mode = '';
Query OK, 0 rows affected (0.00 sec)

mysql> create table a (id int primary key,b  varchar(10) not null default '');
Query OK, 0 rows affected (0.09 sec)

mysql> insert into a values(4, null);
Query OK, 1 row affected, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+---------------------------+
| Level   | Code | Message                   |
+---------+------+---------------------------+
| Warning | 1048 | Column 'b' cannot be null |
+---------+------+---------------------------+
1 row in set (0.00 sec)

4. What is your TiDB version? (Required)

all version has this issue

mysql> select version();
+--------------------+
| version()          |
+--------------------+
| 8.0.11-TiDB-v8.1.0 |
+--------------------+
1 row in set (0.00 sec)

[yiduoyunQ]

mysql behaviour is correct

mysql v8.3

mysql v5.7