As you know,we always design database again and again. There are too much tables in these databases.
And also there are too many data fields are same ,like zip code,telephone,email,md5,loginid,password,create time ... etc
I always think how to design these field's data type and length.always,even i defined some rule before.
So, I want some function can help me add some new data type like email(varchar (20)),zip code (varchar 6). Bla bla bla.
I had do some research :"Sql server" and "Oracle" can do this like 'create type ...' or 'sp_addtype' .But there is no way for MySql.
