SQL表中1个字符代码列的最佳数据类型是什么？

this is not a primary key, but merely used as a marker in existing system that marks these items with a 1 letter code ie 'N' for new, 'R' for return, etc. I was going to go with a varchar(50) as the data type but wondering if there's anything wrong with say varchar(2) instead aiming for efficiency. thx!this is not a primary key, but merely used as a