使用 COALESCE 代替 CASE WHEN

SELECT COUNT(*) FROM (SELECT max(u.id) id, max(u.real_Name) AS realName, max(u.account) account, max(u.remark) remark, max(u.status) status, max(u.mobile_Status) mobileStatus, CASE WHEN GROUP_CONCAT(r.id) IS NULL THEN "-" ELSE GROUP_CONCAT(r.id) END AS userRoles, CASE WHEN GROUP_CONCAT(r.role_name) IS NULL THEN "-" ELSE GROUP_CONCAT(r.role_name) END AS userRoleNames FROM t_user_info u LEFT JOIN t_ref_role_user ru ON ru.user_id = u.id LEFT JOIN t_role_info r ON r.id = ru.role_id LEFT JOIN t_ref_user_tenant ut ON ut.user_id = u.id WHERE u.deleted = '0' GROUP BY u.id ORDER BY u.create_time DESC)

改为

SELECT COUNT(*) FROM (
SELECT
max(u.id) id,
max(u.real_Name) AS realName,
max(u.account) account,
max(u.remark) remark,
max(u.status) status,
max(u.mobile_Status) mobileStatus,
COALESCE(GROUP_CONCAT(r.id), '-') AS userRoles,
COALESCE(GROUP_CONCAT(r.role_name), '-') AS userRoleNames
FROM t_user_info u
LEFT JOIN t_ref_role_user ru ON ru.user_id = u.id
LEFT JOIN t_role_info r ON r.id = ru.role_id
LEFT JOIN t_ref_user_tenant ut ON ut.user_id = u.id
WHERE u.deleted = '0'
GROUP BY u.id
ORDER BY u.create_time DESC
) TOTAL;