gistfile1.txt

MariaDB [test]> create table t3 (b blob, v varchar(8));
Query OK, 0 rows affected (0.50 sec)

MariaDB [test]> insert into t3 values ('','');
Query OK, 1 row affected (0.07 sec)

MariaDB [test]> select * from t3;
+------+------+
| b    | v    |
+------+------+
|      |      |
+------+------+
1 row in set (0.00 sec)

MariaDB [test]> select b+1, v+1 from t3;
+------+------+
| b+1  | v+1  |
+------+------+
|    1 |    1 |
+------+------+
1 row in set, 2 warnings (0.00 sec)

MariaDB [test]> show warnings;
+---------+------+--------------------------------------+
| Level   | Code | Message                              |
+---------+------+--------------------------------------+
| Warning | 1292 | Truncated incorrect DOUBLE value: '' |
| Warning | 1292 | Truncated incorrect DOUBLE value: '' |
+---------+------+--------------------------------------+
2 rows in set (0.00 sec)

MariaDB [test]> select b+1 from t3;
+------+
| b+1  |
+------+
|    1 |
+------+
1 row in set, 1 warning (0.00 sec)

MariaDB [test]> select v+1 from t3;
+------+
| v+1  |
+------+
|    1 |
+------+
1 row in set, 1 warning (0.00 sec)