如何删除指定某一列里的所有数据 保留列名 sql语句

Question

比如 现在有表
student subject grade
---------------------------
student1 语文 80
student1 数学 70
student1 英语 60
student2 语文 90
student2 数学 80
student2 英语 100
------------------------------------------------------要把他变成这样 把student 那一列的内容都删除掉
student subject grade
---------------------------
         语文 80
         数学 70
         英语 60
         语文 90
         数学 80
         英语 100

Answer 1

update tablename set student='' 
你的student这个不是主键 没有指定不能为null吧？

Answer 2

update table set student = null;

Answer 3

SQL> select * from std;STUDENT         SUBJECT              GRADE
--------------- --------------- ----------
student1        语文                    80
student1        数学                    70
student1        英语                    60
student2        语文                    90
student2        数学                    80
student2        英语                   1006 rows selectedSQL> update std set student=null;6 rows updatedSQL> commit;Commit completeSQL> select * from std;STUDENT         SUBJECT              GRADE
--------------- --------------- ----------
                语文                    80
                数学                    70
                英语                    60
                语文                    90
                数学                    80
                英语                   1006 rows selectedSQL> 

Answer 4

update 表名 set student=‘’;