SELECT t.* FROM ( SELECT DISTINCT case_id,node_start_time FROM mediate_case_node_log ORDER BY node_start_time DESC ) t GROUP BY t.case_id
LIMIT 有限制
SELECT t.* FROM ( SELECT case_id,node_start_time FROM mediate_case_node_log ORDER BY node_start_time DESC LIMIT 1000000) t GROUP BY t.case_id