-- 添加客服在线状态字段
-- support_status: online(在线), offline(离线), busy(忙碌)

ALTER TABLE admin_users
ADD COLUMN support_status VARCHAR(16) NOT NULL DEFAULT 'offline' COMMENT '客服状态: online在线, offline离线, busy忙碌';

-- 为查询客服状态添加索引
CREATE INDEX idx_admin_users_support_status ON admin_users(support_status);