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'
用or写了半天,看到题解才懂,题目要的是分别查看、不去重,所以用union all
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'
用or写了半天,看到题解才懂,题目要的是分别查看、不去重,所以用union all