SQL语句修改表结构，如图所示,该如何处理_Sql Server

SQL语句修改表结构，如图所示

这个表，主键，由工程名改成了工程ID，有3个字段的字符串长度由50变成了max，怎么改啊？

------解决方案--------------------

SQL code

alter table Project drop constraint DF_IDalter table Project add constraint [新约束名] primary key([列名])
------解决方案--------------------
竟然没一个会的……
   DECLARE @Constraint_Name varchar (200) 
   
   select @Constraint_Name = Name  
   from dbo.sysobjects  
   where Xtype = 'PK'  
         and Parent_Obj = (select [ID]  
                                 from dbo.sysobjects  
                                 where id = object_id(N'admin')  
        and OBJECTPROPERTY(id, N'IsUserTable') = 1) 
   
   EXEC ('alter table admin drop constraint [email protected]_Name )