stata关于append函数，请大神看下我的命令有什么问题吗？为啥出现这样的错误

 use E:\stata1\金融密度2.dta,clear

append using E:\stata1\金融密度1

variable A is int in master but str8 in using data

    You could specify append's force option to ignore this numeric/string

    mismatch.  The using variable would then be treated as if it contained

    numeric missing value.

出现了这样的问题