PHP mysql PDO refuses to set NULL value
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I am unable to set a nullable field with a default value of null to null using mysql pdo. I can do it using straight sql.

I have tried: (mostly from this question http://stackoverflow.com/questions/1391777/how-do-i-insert-null-values-using-pdo)

1. Null Int 

        bindValue(':param', null, PDO::PARAM_INT);

2. Null Null

        bindValue(':param', null, PDO::PARAM_NULL);

3. 'Null', Int

        bindValue(':param', 'NULL', PDO::PARAM_INT);

4. 'Null', Null

        bindValue(':param', 'NULL', PDO::PARAM_NULL);

5. Null

        bindValue(':param', null);

6. 'Null'

        bindValue(':param', 'NULL');

7. and the `bindParam` counterparts of 5 and 6 with a variable that held the value of the binding.

**Everything from PDO results in the value being set to 0.**

**PHP Version:** `PHP 5.3.2-1ubuntu4.10`

**MYSQL SERVER VERSION:** `5.1.63-0ubuntu0.10.04.1`