since the original post is kind of vague, 3 possible scenarios here:
1. there's one table for customers which has a column for each question.
-- In this case you want to insert a new column for the new question with the default value set to 0. This would require an ALTER query.
2. there's one table for questions. with a different column for each customer.
-- In this case you want to insert a new row for the new question with the default value set to 0. This would require an INSERT query, with the value for each customer column set to 0.
Neither of these seem likely.
3. There a table for customers, a table for questions, and a 3rd table for customer answers. the third table has a one to one mapping as in
| key | customer_id | question_id | answer |
-- Since this is a new question (let's say question 17), you want to INSERT a new row for the new question_id for each customer_id. I assume this is the scenario at hand. For that, you probably want something like this:
| INSERT INTO answers (customer_id, question_id, answer) SELECT DISTINCT customers.id, 17, 0 from customers; |