$sqlCondition = "IFNULL(_table_name.value, _table_name_default.value) REGEXP '^[^a-zA-Z]'"
$collection->getSelect()->where($sqlCondition)
$sqlCondition = "IFNULL(_table_name.value, _table_name_default.value) REGEXP '^[^a-zA-Z]'"
$collection->getSelect()->where($sqlCondition)