mysql - 求 alter column , change column , modify column 区别

Question

在Mysql 里边 Alter TABLE 子选项中 alter column , change column , modify column 有什么区别？

如果有一张大表，执行不同的选项会有什么差异？
求解答

Answer 1

ALTER COLUMN: Set or remove the default value of a column (very fast operation)
Example:

alter table film alter column rental_duration set default 5;  
alter table film alter column rental_duration drop default;

CHANGE COLUMN: Column renaming, column type change and column position movement
Example:

ALTER TABLE MyTable CHANGE COLUMN foo bar VARCHAR(32) NOT NULL FIRST;  
ALTER TABLE MyTable CHANGE COLUMN foo bar VARCHAR(32) NOT NULL AFTER baz; 

MODIFY COLUMN: Except that the column cannot be renamed, it does the same job as CHANGE COLUMN
Example:

ALTER TABLE MyTable MODIFY COLUMN foo VARCHAR(32) NOT NULL AFTER baz;

Quoted from: http://blog.csdn.net/dba_waterbin/article/details/17884549