sql 语句中字符类型的转换问题，在线等！！！急！！！

select 'http//'+ID+'.html' as LINK from A
ID的字符类型是bigint的，出现错误提示：“从数据类型 varchar 转换为 bigint 时出错。”
求解决语法！！！

 select 'http//'+convert(varchar(20),ID)+'.html' as LINK from A 

select 'http//'+cast t(ID as varchar(50))+'.html' as LINK from A