-- 添加列
alter table student add dept varchar(20);
+-------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| sid | int | NO | PRI | NULL | auto_increment |
| name | varchar(20) | YES | UNI | NULL | |
| age | int | NO | | NULL | |
| dept | varchar(20) | YES | | NULL | |
+-------+-------------+------+-----+---------+----------------+
-- 修改列名和类型
alter table student change dept department varchar(30);
+------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+----------------+
| sid | int | NO | PRI | NULL | auto_increment |
| name | varchar(20) | YES | UNI | NULL | |
| age | int | NO | | NULL | |
| department | varchar(30) | YES | | NULL | |
+------------+-------------+------+-----+---------+----------------+
-- 修改表删除列
alter table student drop department;
+-------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| sid | int | NO | PRI | NULL | auto_increment |
| name | varchar(20) | YES | UNI | NULL | |
| age | int | NO | | NULL | |
+-------+-------------+------+-----+---------+----------------+
-- 修改表名
rename table student to stu;
+---------------------+
| Tables_in_database1 |
+---------------------+
| stu |
+---------------------+
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-- 数据插入
insert into student (sid,name,age)values(5,'老七',19),(6,'老八',20);
insert into student(sid,age) values(100,20);
insert into student values(7,'老九',21),(8,'老十',22);
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