consider unsigned int for built-in function truncate

[XuHuaiyu]

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

CREATE TABLE `t` (
  `a` bigint(20) UNSIGNED DEFAULT NULL
);
insert into t value(cast(a as unsigned));;

2. What did you expect to see?

mysql> select truncate(a, 1) from t;
+----------------------+
| truncate(a, 1)       |
+----------------------+
| 18446744073709551615 |
+----------------------+
1 row in set (0.01 sec)

3. What did you see instead?

tidb> select truncate(a, 1) from t;
+----------------+
| truncate(a, 1) |
+----------------+
|           NULL |
+----------------+
1 row in set (0.00 sec)

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

tidb> select tidb_Version();
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_Version()                                                                                                                                                                                                                                                                                                                      |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v2.1.0-rc.1-41-g3d891d9c2
Git Commit Hash: 3d891d9c2666a4812f77fc286d696f279a9e8e4c
Git Branch: master
UTC Build Time: 2018-09-03 08:14:20
GoVersion: go version go1.10.3 darwin/amd64
Race Enabled: false
TiKV Min Version: 2.1.0-alpha.1-ff3dd160846b7d1aed9079c389fc188f7f5ea13e
Check Table Before Drop: false |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[mz1999]

I executed the above SQL statements on MySQL, Why didn't I get the expected results?

CREATE TABLE `t` (
  `a` bigint(20) UNSIGNED DEFAULT NULL
);
insert into t value(cast(a as unsigned));

mysql> select truncate(a, 1) from t;
+----------------+
| truncate(a, 1) |
+----------------+
|           NULL |
+----------------+
1 row in set (0.01 sec)

MySQL version is 5.7

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.22    |
+-----------+
1 row in set (0.00 sec)

[winoros]

@mz1999
The insert sql should be same with insert into t value(cast(DEFAULT as unsigned));
cast(default as unsigned) => cast(null as unsigned) => null
truncate(NULL, 1) = NULL

[zz-jason]

discovered in tikv/tikv#3532

[XuHuaiyu]

Sorry for the wrong reproducible steps I mentioned in the description,
which I wanted to report is the same as #7615 .

So I will close this issue, and reopen that one.

[XuHuaiyu]

Sorry for the wrong reproducible steps I mentioned in the description,
which I wanted to report is the same as #7615 .

So I will close this issue, and reopen that one.