Warnings are not reset on SELECT not touching any tables

mysql 5.7 >  select cast('foo' as unsigned);

+-------------------------+

| cast('foo' as unsigned) |

+-------------------------+

|                       0 |

+-------------------------+

1 row in set, 1 warning (0.00 sec)

mysql 5.7 > show warnings;

+---------+------+------------------------------------------+

| Level   | Code | Message                                  |

+---------+------+------------------------------------------+

| Warning | 1292 | Truncated incorrect INTEGER value: 'foo' |

+---------+------+------------------------------------------+

1 row in set (0.00 sec)

mysql 5.7 > select cast('bar' as unsigned);

+-------------------------+

| cast('bar' as unsigned) |

+-------------------------+

|                       0 |

+-------------------------+

1 row in set, 1 warning (0.00 sec)

mysql 5.7 > show warnings;

+---------+------+------------------------------------------+

| Level   | Code | Message                                  |

+---------+------+------------------------------------------+

| Warning | 1292 | Truncated incorrect INTEGER value: 'bar' |

+---------+------+------------------------------------------+

1 row in set (0.00 sec)

mysql 5.7 > select cast(42.0 as unsigned);

+------------------------+

| cast(42.0 as unsigned) |

+------------------------+

|                     42 |

+------------------------+

1 row in set (0.00 sec)

mysql 5.7 > show warnings;

Empty set (0.00 sec)

mysql 5.7 > 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 5.7 > show warnings;

Empty set (0.00 sec)

[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)