[8 Dec 15:21] Miguel Solorzano

C:\dbs>c:\dbs\5.6\bin\mysql -uroot --port=3560 --debug-info
--prompt="mysql 5.6 > "
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.23 Source distribution 2014.12.02

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights
reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input
statement.

mysql 5.6 >  select cast('foo' as unsigned);
+-------------------------+
| cast('foo' as unsigned) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.00 sec)

mysql 5.6 > show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'foo' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

mysql 5.6 > select cast('bar' as unsigned);
+-------------------------+
| cast('bar' as unsigned) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.00 sec)

mysql 5.6 > show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

mysql 5.6 > select cast(42.0 as unsigned);
+------------------------+
| cast(42.0 as unsigned) |
+------------------------+
|                     42 |
+------------------------+
1 row in set (0.00 sec)

mysql 5.6 > show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

mysql 5.6 > select cast(42.0 as unsigned) from mysql.user limit 1;
+------------------------+
| cast(42.0 as unsigned) |
+------------------------+
|                     42 |
+------------------------+
1 row in set (0.00 sec)

mysql 5.6 > show warnings;
Empty set (0.00 sec)

mysql 5.6 >


------------------------------------------------------------------------

[8 Dec 14:35] Hartmut Holzgraefe

Description:
Warnings are not reset on successful execution of a SELECT statement
without FROM clause or when using the dummy "FROM DUAL". If the
statement raises a new warning though the old warnings are replaced.

How to repeat:
MySQL [test]> select cast('foo' as unsigned);
+-------------------------+
| cast('foo' as unsigned) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.00 sec)

MySQL [test]> show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'foo' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

MySQL [test]> select cast('bar' as unsigned);
+-------------------------+
| cast('bar' as unsigned) |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set, 1 warning (0.00 sec)

MySQL [test]> show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

MySQL [test]> select cast(42.0 as unsigned);
+------------------------+
| cast(42.0 as unsigned) |
+------------------------+
|                     42 |
+------------------------+
1 row in set (0.00 sec)

MySQL [test]> show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

MySQL [test]> select cast(42.0 as unsigned) from dual;
+------------------------+
| cast(42.0 as unsigned) |
+------------------------+
|                     42 |
+------------------------+
1 row in set (0.00 sec)

MySQL [test]> show warnings;
+---------+------+------------------------------------------+
| Level   | Code | Message                                  |
+---------+------+------------------------------------------+
| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |
+---------+------+------------------------------------------+
1 row in set (0.00 sec)

MySQL [test]> select cast(42.0 as unsigned) from mysql.user limit 1;
+------------------------+
| cast(42.0 as unsigned) |
+------------------------+
|                     42 |
+------------------------+
1 row in set (0.00 sec)

MySQL [test]> show warnings;
Empty set (0.00 sec)