SELECT 0 LIKE 'a string' should not be true.

[SunRunAway]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

SELECT 0 LIKE 'a string'

2. What did you expect to see?

False with no warning.

mysql> SELECT 0 LIKE 'a string';
+-------------------+
| 0 LIKE 'a string' |
+-------------------+
|                 0 |
+-------------------+
1 row in set (0.00 sec)

3. What did you see instead?

mysql> SELECT 0 LIKE 'a string';
+-------------------+
| 0 LIKE 'a string' |
+-------------------+
|                 1 |
+-------------------+
1 row in set, 1 warning (0.00 sec)

mysql> show warnings;
+---------+------+----------------+
| Level   | Code | Message        |
+---------+------+----------------+
| Warning | 1265 | Data Truncated |
+---------+------+----------------+
1 row in set (0.01 sec)

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   fdbc149