mysql - sql 语句更改表结构，添加多个列，怎么写？

Question

添加一个列是这样的：
ALTER TABLE tablename ADD 列名 数据类型
那多个呢？

Answer 1

ALTER TABLE tablename ADD COLUMN column name data type, ADD COLUMN column name data type;

Answer 2

Add column
alter table mytable add name varchar(10)
Delete column
alter table mytable drop column name
Modify column type
alter table mytable alter column name nvarchar(10 )

Answer 3

Add multiple columns:
alter table mytable add name varchar(10), add name2 varchar(10); you can continue to add
modify
alter table mytable modify name varchar(10), modify name2 varchar (10);You can continue to add