Inserting NULL into NOT NULL columns with Default Value

Question

For a bit of background, we use Zend Framework 2 and Doctrine at work. Doctrine will always insert NULL for values we do not popul

Answer 1

According to the documentation, everything works as expected.

Test case:

mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.6.16    |
+-----------+
1 row in set (0.00 sec)

mysql> SELECT @@GLOBAL.sql_mode 'sql_mode::GLOBAL',
              @@SESSION.sql_mode 'sql_mode::SESSION';
+------------------------+------------------------+
| sql_mode::GLOBAL       | sql_mode::SESSION      |
+------------------------+------------------------+
| NO_ENGINE_SUBSTITUTION | NO_ENGINE_SUBSTITUTION |
+------------------------+------------------------+
1 row in set (0.00 sec)

mysql> SET SESSION sql_mode := 'NO_AUTO_VALUE_ON_ZERO,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @@GLOBAL.sql_mode 'sql_mode::GLOBAL',
              @@SESSION.sql_mode 'sql_mode::SESSION';
+------------------------+-----------------------------------------------------------------------------------------------------------------+
| sql_mode::GLOBAL       | sql_mode::SESSION                                                                                               |
+------------------------+-----------------------------------------------------------------------------------------------------------------+
| NO_ENGINE_SUBSTITUTION | NO_AUTO_VALUE_ON_ZERO,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+------------------------+-----------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SHOW CREATE TABLE `table_name`;
+------------+----------------------------------------------------------------------------+
| Table      | Create Table                                                               |
+------------+----------------------------------------------------------------------------+
| table_name | CREATE TABLE `table_name` (                                                |
|            |        `id` INT(11) UNSIGNED NOT NULL,                                     |
|            |        `field` VARCHAR(20) DEFAULT NULL,                                   |
|            |        `field_with_default_value` VARCHAR(20) NOT NULL DEFAULT 'myDefault' |
|            | ) ENGINE=InnoDB DEFAULT CHARSET=latin1                                     |
+------------+----------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> INSERT INTO `table_name`(`id`, `field`, `field_with_default_value`)
       VALUES
       (1, 'Value', NULL);
ERROR 1048 (23000): Column 'field_with_default_value' cannot be null

Is it possible to post the relevant part of the structure of your table to see how we can help?

UPDATE

MySQL 5.7, using triggers, can provide a possible solution to the problem:

Changes in MySQL 5.7.1 (2013-04-23, Milestone 11)

...

• If a column is declared as NOT NULL, it is not permitted to insert NULL into the column or update it to NULL. However, this constraint was enforced even if there was a BEFORE INSERT (or BEFORE UPDATE trigger) that set the column to a non-NULL value. Now the constraint is checked at the end of the statement, per the SQL standard. (Bug #6295, Bug#11744964).

...

Possible solution:

mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.4-m14 |
+-----------+
1 row in set (0.00 sec)

mysql> DELIMITER $$

mysql> CREATE TRIGGER `trg_bi_set_default_value` BEFORE INSERT ON `table_name`
       FOR EACH ROW
       BEGIN
          IF (NEW.`field_with_default_value` IS NULL) THEN
             SET NEW.`field_with_default_value` := 
                (SELECT `COLUMN_DEFAULT`
                 FROM `information_schema`.`COLUMNS`
                 WHERE `TABLE_SCHEMA` = DATABASE() AND 
                       `TABLE_NAME` = 'table_name' AND
                       `COLUMN_NAME` = 'field_with_default_value');
          END IF;
       END$$

mysql> DELIMITER ;

mysql> INSERT INTO `table_name`(`id`, `field`, `field_with_default_value`)
       VALUES
       (1, 'Value', NULL);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT `id`, `field`, `field_with_default_value` FROM `table_name`;
+----+-------+--------------------------+
| id | field | field_with_default_value |
+----+-------+--------------------------+
|  1 | Value | myDefault                |
+----+-------+--------------------------+
1 row in set (0.00 sec)