# or默认去重
# select device_id, gender, age, gpa from user_profile WHERE university = '山东大学' or gender = 'male';
# 使用union all 不去重
select device_id, gender, age, gpa from user_profile WHERE university = '山东大学'
union all
select device_id, gender, age, gpa from user_profile where
gender = 'male';
题目 是 或的关系 并且不去重 所以不用or、换union all