Disabling STRICT_TRANS_TABLES should allow NULL insert into NOT NULL column with default value

[wjhuang2016]

Bug Report

1. What did you do?

create table t1 (id int NOT NULL DEFAULT 8);
SET sql_mode = '';
insert into t1 values (1), (NULL), (2);

2. What did you expect to see?

mysql> create table t1 (id int NOT NULL DEFAULT 8);
Query OK, 0 rows affected (0.06 sec)

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

mysql> insert into t1 values (1), (NULL), (2);
Query OK, 3 rows affected, 1 warning (0.03 sec)
Records: 3  Duplicates: 0  Warnings: 1

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

mysql> select * from t1;
+----+
| id |
+----+
|  1 |
|  0 |
|  2 |
+----+
3 rows in set (0.00 sec)

3. What did you see instead?

mysql> create table t1 (id int NOT NULL DEFAULT 8);
Query OK, 0 rows affected (0.02 sec)

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

mysql> insert into t1 values (1), (NULL), (2);
ERROR 1048 (23000): Column 'id' cannot be null

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   master

[zimulala]

@wjhuang2016 Thanks for your feedback!
We may not support it in the short term.

[ghost]

Confirming I can reproduce this against master. The specific issue is that TiDB does not impliment STRICT_TRANS_TABLES as OFF correctly:

drop table if exists t1;
create table t1 (id int NOT NULL DEFAULT 8);
SET sql_mode = 'STRICT_TRANS_TABLES';
insert into t1 values (1), (NULL), (2);
SET sql_mode = '';
insert into t1 values (1), (NULL), (2);

..

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

mysql> insert into t1 values (1), (NULL), (2); -- should fail (correct)
ERROR 1048 (23000): Column 'id' cannot be null
mysql> SET sql_mode = '';
Query OK, 0 rows affected (0.00 sec)

mysql> insert into t1 values (1), (NULL), (2); -- should succeed (fails incorrectly)
ERROR 1048 (23000): Column 'id' cannot be null

mysql> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v4.0.0-beta.2-771-gca41972fb
Edition: Community
Git Commit Hash: ca41972fbac068c8a5de107d9075f09ac68842ac
Git Branch: master
UTC Build Time: 2020-07-14 02:41:21
GoVersion: go1.13
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
1 row in set (0.00 sec)

[watchpoints]

@wjhuang2016 Thanks for your feedback!
We may not support it in the short term.

@zimulala this issue is not picked up?

[wjhuang2016]

@watchpoints I had a PR for it, and I will reopen it soon.

[ti-srebot]

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