COUNT计数

练习内容

-- 统计用户总数\nSELECT COUNT(*) AS total_users FROM users;\n\n-- 统计活跃用户数\nSELECT COUNT(*) AS active_users\nFROM users WHERE status = 'active';\n\n-- 统计不同状态的用户数\nSELECT status, COUNT(*) AS count\nFROM users