简化MySQL语句：统计已转移和未转移人数

{"title":"简化MySQL语句：统计已转移和未转移人数","description":"本文介绍了如何简化一个复杂的MySQL语句，该语句用于统计已转移和未转移人数。","keywords":"MySQL, SQL, 简化, 优化, 统计, 转移, 人数","content":"该MySQL语句可以简化如下：\n\nSELECT\n CASE\n WHEN c.states > 0 THEN '已转移人数' ELSE '未转移人数' END AS states,\n COUNT(*) AS num\nFROM\n cx_govern_emergency_warn_middle_manager a\n JOIN (SELECT id FROM cx_govern_emergency_warn_manager ORDER BY id DESC LIMIT 1) b ON a.warn_id = b.id\nGROUP BY\n states"}