-- 检查学生数据
SELECT 
    ca.id,
    ca.student_id,
    u.user_id,
    u.nick_name,
    u.user_name
FROM course_assignment ca
LEFT JOIN sys_user u ON ca.student_id = u.user_id
WHERE ca.student_id IN (1011, 9535, 116, 1013, 9534, 9538)
ORDER BY ca.student_id;

-- 检查sys_user表中是否有这些用户
SELECT user_id, nick_name, user_name, remark
FROM sys_user 
WHERE user_id IN (1011, 9535, 116, 1013, 9534, 9538)
ORDER BY user_id;