Confirm updating to NULL.
function testSimpleNullUpdate() {
$this
->ensureSampleDataNull();
$num_updated = db_update('test_null')
->fields(array(
'age' => NULL,
))
->condition('name', 'Kermit')
->execute();
$this
->assertIdentical($num_updated, 1, 'Updated 1 record.');
$saved_age = db_query('SELECT age FROM {test_null} WHERE name = :name', array(
':name' => 'Kermit',
))
->fetchField();
$this
->assertNull($saved_age, 'Updated name successfully.');
}