we can insert negative value to unsinged float column sometimes

[lcwangchao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table tf(a float(1, 0) unsigned);
set sql_mode='';
insert into tf values("-100");
select * from tf;

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

In MySQL, the inserted value should be zero:

mysql> select * from tf;
+------+
| a    |
+------+
|    0 |
+------+
1 row in set (0.00 sec)

3. What did you see instead (Required)

A negative value is inserted in TiDB:

mysql> select * from tf;
+------+
| a    |
+------+
|   -9 |
+------+
1 row in set (0.00 sec)

4. What is your TiDB version? (Required)

master, But I think it affect all versions.