Problem Statement

MySQL: Group Field Select the expression that causes a MySQL error when used with `GROUP BY customer_id`. SELECT customer_id, ANY_VALUE(amount) FROM transactions GROUP BY customer_id SELECT customer_id, RAND(amount) FROM transactions GROUP BY customer_id SELECT customer_id, SUBSTRING_INDEX(GROUP_CONCAT(amount ORDER BY RAND()), ',', 1) FROM transactions GROUP BY customer_id None of the above; all expressions are correct